field.h

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#ifndef FIELD_INCLUDED
#define FIELD_INCLUDED
 
/* Copyright (c) 2000, 2025, Oracle and/or its affiliates.
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
   This program is designed to work with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have either included with
   the program or referenced in the documentation.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#include <assert.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
 
#include <algorithm>
#include <optional>
 
#include "decimal.h"      // E_DEC_OOM
#include "field_types.h"  // enum_field_types
#include "lex_string.h"
#include "my_alloc.h"
#include "my_base.h"  // ha_storage_media
#include "my_bitmap.h"
#include "my_dbug.h"
#include "my_double2ulonglong.h"
#include "my_inttypes.h"
#include "my_temporal.h"
#include "my_time.h"  // MYSQL_TIME_NOTE_TRUNCATED
#include "mysql/binlog/event/export/binary_log_funcs.h"  // my_time_binary_length
#include "mysql/strings/dtoa.h"
#include "mysql/strings/m_ctype.h"
#include "mysql/udf_registration_types.h"
#include "mysql_com.h"
#include "mysql_time.h"
#include "sql/dd/types/column.h"
#include "sql/field_common_properties.h"
#include "sql/gis/srid.h"
#include "sql/sql_bitmap.h"
#include "sql/sql_const.h"
#include "sql/sql_error.h"  // Sql_condition
#include "sql/table.h"
#include "sql_string.h"  // String
#include "template_utils.h"
#include "vector-common/vector_constants.h"  // max_dimensions
 
class Create_field;
class CostOfItem;
class Field;
class Field_bit;
class Field_bit_as_char;
class Field_blob;
class Field_decimal;
class Field_double;
class Field_enum;
class Field_float;
class Field_json;
class Field_long;
class Field_longlong;
class Field_medium;
class Field_new_decimal;
class Field_date;
class Field_num;
class Field_real;
class Field_set;
class Field_short;
class Field_str;
class Field_string;
class Field_temporal;
class Field_temporal_with_date;
class Field_temporal_with_date_and_time;
class Field_time;
class Field_timestamp;
class Field_tiny;
class Field_varstring;
class Field_year;
class Item;
class Item_field;
class Json_array;
class Json_diff_vector;
class Json_wrapper;
class KEY;
class Protocol;
class Relay_log_info;
class Send_field;
class THD;
class Time_zone;
class my_decimal;
struct my_timeval;
struct TYPELIB;
 
/*
  Inside an in-memory data record, memory pointers to pieces of the
  record (like BLOBs) are stored in their native byte order and in
  this amount of bytes.
*/
#define portable_sizeof_char_ptr 8
 
/*
 
Field class hierarchy
 
 
Field (abstract)
|
+--Field_bit
|  +--Field_bit_as_char
|
+--Field_num (abstract)
|  |  +--Field_real (abstract)
|  |     +--Field_decimal
|  |     +--Field_float
|  |     +--Field_double
|  |
|  +--Field_new_decimal
|  +--Field_short
|  +--Field_medium
|  +--Field_long
|  +--Field_longlong
|  +--Field_tiny
|     +--Field_year
|
+--Field_str (abstract)
|  +--Field_longstr
|  |  +--Field_string
|  |  +--Field_varstring
|  |  +--Field_blob
|  |     +--Field_geom
|  |     +--Field_json
|  |        +--Field_typed_array
|  |     +--Field_vector
|  |
|  +--Field_null
|  +--Field_enum
|     +--Field_set
|
+--Field_temporal (abstract)
   +--Field_time
   |
   +--Field_temporal_with_date (abstract)
      +--Field_date
      +--Field_temporal_with_date_and_time (abstract)
         +--Field_timestamp
         +--Field_datetime
*/
 
enum enum_check_fields : int {
  CHECK_FIELD_IGNORE = 0,
  CHECK_FIELD_WARN,
  CHECK_FIELD_ERROR_FOR_NULL
};
 
/// For use @see DTCollation::aggregate()
enum Derivation {
  DERIVATION_NONE = 7,
  DERIVATION_NULL = 6,
  DERIVATION_NUMERIC = 5,
  DERIVATION_COERCIBLE = 4,
  DERIVATION_SYSCONST = 3,
  DERIVATION_IMPLICIT = 2,
  DERIVATION_UNUSED = 1,  // Avoids changes in COERCIBILITY() results
  DERIVATION_EXPLICIT = 0
};
 
/* Specifies data storage format for individual columns */
enum column_format_type {
  COLUMN_FORMAT_TYPE_DEFAULT = 0, /* Not specified (use engine default) */
  COLUMN_FORMAT_TYPE_FIXED = 1,   /* FIXED format */
  COLUMN_FORMAT_TYPE_DYNAMIC = 2  /* DYNAMIC format */
};
 
/**
  Status when storing a value in a field or converting from one
  datatype to another. The values should be listed in order of
  increasing seriousness so that if two type_conversion_status
  variables are compared, the bigger one is most serious.
*/
enum type_conversion_status {
  /// Storage/conversion went fine.
  TYPE_OK = 0,
  /**
    A minor problem when converting between temporal values, e.g.
    if datetime is converted to date the time information is lost.
  */
  TYPE_NOTE_TIME_TRUNCATED,
  /**
    Value was stored, but something was cut. What was cut is
    considered insignificant enough to only issue a note. Example:
    trying to store a number with 5 decimal places into a field that
    can only store 3 decimals. The number rounded to 3 decimal places
    should be stored. Another example: storing the string "foo " into
    a VARCHAR(3). The string "foo" is stored in this case, so only
    whitespace is cut.
  */
  TYPE_NOTE_TRUNCATED,
  /**
    Value outside min/max limit of datatype. The min/max value is
    stored by Field::store() instead (if applicable)
  */
  TYPE_WARN_OUT_OF_RANGE,
  /**
    Value was stored, but something was cut. What was cut is
    considered significant enough to issue a warning. Example: storing
    the string "foo" into a VARCHAR(2). The string "fo" is stored in
    this case. Another example: storing the string "2010-01-01foo"
    into a DATE. The garbage in the end of the string is cut in this
    case.
  */
  TYPE_WARN_TRUNCATED,
  /**
    Value has invalid string data. When present in a predicate with
    equality operator, range optimizer returns an impossible where.
  */
  TYPE_WARN_INVALID_STRING,
  /// Trying to store NULL in a NOT NULL field.
  TYPE_ERR_NULL_CONSTRAINT_VIOLATION,
  /**
    Store/convert incompatible values, like converting "foo" to a
    date.
  */
  TYPE_ERR_BAD_VALUE,
  /// Out of memory
  TYPE_ERR_OOM
};
 
/*
  Some defines for exit codes for ::is_equal class functions.
*/
#define IS_EQUAL_NO 0
#define IS_EQUAL_YES 1
#define IS_EQUAL_PACK_LENGTH 2
 
#define my_charset_numeric my_charset_latin1
#define MY_REPERTOIRE_NUMERIC MY_REPERTOIRE_ASCII
 
/**
  Check if one can copy from “from” to “to” with a simple memcpy(), with
  pack_length() as the length. This is the case if the types of the two fields
  are the same and we don't have special copying rules for the type
  (e.g., blobs, which require allocation, or time functions that require
  checking for special SQL modes).
 
  You should never call this with to == from, as such copies are no-ops
  and memcpy() has undefined behavior with overlapping memory areas.
 */
bool fields_are_memcpyable(const Field *to, const Field *from);
 
/**
  Copy the value in "from" (assumed to be non-NULL) to "to", doing any
  required conversions in the process.
 
  Note that you should only call this if fields_are_memcpyable() is false,
  since it does an actual conversion on the slow path (and it is not properly
  tested whether it gives the correct result in all cases if
  fields_are_memcpyable() is true).
 
  You should never call this with to == from, as they are no-ops.
 */
type_conversion_status field_conv_slow(Field *to, const Field *from);
 
inline uint get_enum_pack_length(int elements) {
  return elements < 256 ? 1 : 2;
}
 
inline uint get_set_pack_length(int elements) {
  const uint len = (elements + 7) / 8;
  return len > 4 ? 8 : len;
}
 
inline type_conversion_status decimal_err_to_type_conv_status(int dec_error) {
  if (dec_error & E_DEC_OOM) return TYPE_ERR_OOM;
 
  if (dec_error & (E_DEC_DIV_ZERO | E_DEC_BAD_NUM)) return TYPE_ERR_BAD_VALUE;
 
  if (dec_error & E_DEC_TRUNCATED) return TYPE_NOTE_TRUNCATED;
 
  if (dec_error & E_DEC_OVERFLOW) return TYPE_WARN_OUT_OF_RANGE;
 
  if (dec_error == E_DEC_OK) return TYPE_OK;
 
  // impossible
  assert(false);
  return TYPE_ERR_BAD_VALUE;
}
 
/**
  Convert warnings returned from str_to_time() and str_to_datetime()
  to their corresponding type_conversion_status codes.
*/
inline type_conversion_status time_warning_to_type_conversion_status(
    const int warn) {
  if (warn & MYSQL_TIME_NOTE_TRUNCATED) return TYPE_NOTE_TIME_TRUNCATED;
 
  if (warn & MYSQL_TIME_WARN_OUT_OF_RANGE) return TYPE_WARN_OUT_OF_RANGE;
 
  if (warn & MYSQL_TIME_WARN_TRUNCATED) return TYPE_NOTE_TRUNCATED;
 
  if (warn & (MYSQL_TIME_WARN_ZERO_DATE | MYSQL_TIME_WARN_ZERO_IN_DATE))
    return TYPE_ERR_BAD_VALUE;
 
  if (warn & MYSQL_TIME_WARN_INVALID_TIMESTAMP)
    // date was fine but pointed to daylight saving time switch gap
    return TYPE_OK;
 
  assert(!warn);
  return TYPE_OK;
}
 
#define ASSERT_COLUMN_MARKED_FOR_READ \
  assert(!table ||                    \
         (!table->read_set || bitmap_is_set(table->read_set, field_index())))
#define ASSERT_COLUMN_MARKED_FOR_WRITE   \
  assert(!table || (!table->write_set || \
                    bitmap_is_set(table->write_set, field_index())))
 
/**
  Tests if field real type is temporal, i.e. represents
  all existing implementations of
  DATE, TIME, DATETIME or TIMESTAMP types in SQL.
 
  @param type    Field real type, as returned by field->real_type()
  @retval true   If field real type is temporal
  @retval false  If field real type is not temporal
*/
inline bool is_temporal_real_type(enum_field_types type) {
  switch (type) {
    case MYSQL_TYPE_TIME2:
    case MYSQL_TYPE_TIMESTAMP2:
    case MYSQL_TYPE_DATETIME2:
      return true;
    default:
      return is_temporal_type(type);
  }
}
 
/**
  Tests if field real type can have "DEFAULT CURRENT_TIMESTAMP",
  i.e. represents TIMESTAMP types in SQL.
 
  @param type    Field type, as returned by field->real_type().
  @retval true   If field real type can have "DEFAULT CURRENT_TIMESTAMP".
  @retval false  If field real type can not have "DEFAULT CURRENT_TIMESTAMP".
*/
inline bool real_type_with_now_as_default(enum_field_types type) {
  return type == MYSQL_TYPE_TIMESTAMP || type == MYSQL_TYPE_TIMESTAMP2 ||
         type == MYSQL_TYPE_DATETIME || type == MYSQL_TYPE_DATETIME2;
}
 
/**
  Tests if field real type can have "ON UPDATE CURRENT_TIMESTAMP",
  i.e. represents TIMESTAMP types in SQL.
 
  @param type    Field type, as returned by field->real_type().
  @retval true   If field real type can have "ON UPDATE CURRENT_TIMESTAMP".
  @retval false  If field real type can not have "ON UPDATE CURRENT_TIMESTAMP".
*/
inline bool real_type_with_now_on_update(enum_field_types type) {
  return type == MYSQL_TYPE_TIMESTAMP || type == MYSQL_TYPE_TIMESTAMP2 ||
         type == MYSQL_TYPE_DATETIME || type == MYSQL_TYPE_DATETIME2;
}
 
/**
  Convert temporal real types as returned by field->real_type()
  to field type as returned by field->type().
 
  @param real_type  Real type.
  @retval           Field type.
*/
inline enum_field_types real_type_to_type(enum_field_types real_type) {
  switch (real_type) {
    case MYSQL_TYPE_TIME2:
      return MYSQL_TYPE_TIME;
    case MYSQL_TYPE_DATETIME2:
      return MYSQL_TYPE_DATETIME;
    case MYSQL_TYPE_TIMESTAMP2:
      return MYSQL_TYPE_TIMESTAMP;
    case MYSQL_TYPE_NEWDATE:
      return MYSQL_TYPE_DATE;
    /* Note: NEWDECIMAL is a type, not only a real_type */
    default:
      return real_type;
  }
}
 
/**
  Return the appropriate MYSQL_TYPE_X_BLOB value based on the
  pack_length.
 
  @param  pack_length pack_length for BLOB
  @retval MYSQL_TYPE_X_BLOB corresponding to pack_length.
*/
inline enum_field_types blob_type_from_pack_length(uint pack_length) {
  DBUG_TRACE;
  switch (pack_length) {
    case 1:
      return MYSQL_TYPE_TINY_BLOB;
    case 2:
      return MYSQL_TYPE_BLOB;
    case 3:
      return MYSQL_TYPE_MEDIUM_BLOB;
    case 4:
      return MYSQL_TYPE_LONG_BLOB;
    default:
      assert(false);
      return MYSQL_TYPE_LONG_BLOB;
  }
}
 
/**
   Copies an integer value to a format comparable with memcmp(). The
   format is characterized by the following:
 
   - The sign bit goes first and is unset for negative values.
   - The representation is big endian.
 
   The function template can be instantiated to copy from little or
   big endian values.
 
   @tparam Is_big_endian True if the source integer is big endian.
 
   @param to          Where to write the integer.
   @param to_length   Size in bytes of the destination buffer.
   @param from        Where to read the integer.
   @param from_length Size in bytes of the source integer
   @param is_unsigned True if the source integer is an unsigned value.
*/
template <bool Is_big_endian>
void copy_integer(uchar *to, size_t to_length, const uchar *from,
                  size_t from_length, bool is_unsigned) {
  if (to_length == 0) return;
  if (Is_big_endian) {
    std::copy(from, from + std::min(to_length, from_length), to);
    if (!is_unsigned)
      to[0] = static_cast<char>(to[0] ^ 128);  // Reverse the sign bit.
  } else {
    const uchar *from_end = from + from_length;
    const uchar *from_start = from_end - std::min(from_length, to_length);
    std::reverse_copy(from_start, from_end, to);
    if (!is_unsigned)
      to[0] = static_cast<char>(to[0] ^ 128);  // Reverse the sign bit.
  }
}
 
/**
  Enum to indicate source for which value generator is used. This is needed
  while unpacking value generator expression and pre-validating the
  expression for generated column, default expression or check constraint.
*/
enum Value_generator_source : short {
  VGS_GENERATED_COLUMN = 0,  // Value generator for GENERATED_COLUMN.
  VGS_DEFAULT_EXPRESSION,    // Value generator for Default expression.
  VGS_CHECK_CONSTRAINT       // Value generator for check constraints.
};
 
/**
  Used for storing information associated with generated column, default
  values generated from expression or check constraint expression.
*/
class Value_generator {
 public:
  /**
    Item representing the generation expression.
    This is non-NULL for every Field of a TABLE, if that field is a generated
    column.
    Contrast this with the Field of a TABLE_SHARE, which has expr_item==NULL
    even if it's a generated column; that makes sense, as an Item tree cannot
    be shared.
  */
  Item *expr_item{nullptr};
  /**
    Text of the expression. Used in only one case:
    - the text read from the DD is put into the Value_generator::expr_str of
    the Field of the TABLE_SHARE; then this expr_str is used as source
    to produce expr_item for the Field of every TABLE derived from this
    TABLE_SHARE.
  */
  LEX_STRING expr_str{nullptr, 0};
 
  /**
    Bit field indicating the type of statement for binary logging.
    It needs to be saved because this is determined only once when it is parsed
    but it needs to be set on the lex for each statement that uses this
    value generator. And since unpacking is done once on table open, it will
    be set for the rest of the statements in bind_value_generator_to_fields.
  */
  uint32 m_backup_binlog_stmt_flags{0};
 
  /// List of all items created when parsing and resolving generated expression
  Item *item_list{nullptr};
  /// Bitmap records base columns which a generated column depends on.
  MY_BITMAP base_columns_map;
 
  enum_field_types get_real_type() const { return field_type; }
 
  void set_field_type(enum_field_types fld_type) { field_type = fld_type; }
 
  /**
     Set the binary log flags in m_backup_binlog_stmt_flags
     @param backup_binlog_stmt_flags the flags to be backed up
  */
  void backup_stmt_unsafe_flags(uint32 backup_binlog_stmt_flags) {
    m_backup_binlog_stmt_flags = backup_binlog_stmt_flags;
  }
 
  /**
    Get the binary log flags from m_backup_binlog_stmt_flags
    @return the flags backed up by unpack_value_generator
  */
  uint32 get_stmt_unsafe_flags() { return m_backup_binlog_stmt_flags; }
 
  bool get_field_stored() const { return stored_in_db; }
  void set_field_stored(bool stored) { stored_in_db = stored; }
  bool register_base_columns(TABLE *table);
  /**
    Get the number of non virtual base columns that this generated
    column needs.
 
    @return number of non virtual base columns
  */
  uint non_virtual_base_columns() const { return num_non_virtual_base_cols; }
 
  /**
     Duplicates a string into expr_str.
 
     @param root MEM_ROOT to use for allocation
     @param src  source string
     @param len  length of 'src' in bytes
  */
  void dup_expr_str(MEM_ROOT *root, const char *src, size_t len);
 
  /**
     Writes the generation expression into a String with proper syntax.
     @param thd  THD
     @param out  output String
  */
  void print_expr(THD *thd, String *out);
 
  /*
   The following data is only updated by the parser and read
   when a Create_field object is created/initialized.
   */
 private:
  /// Real field type
  enum_field_types field_type{MYSQL_TYPE_INVALID};
  /// Indicates if the field is physically stored in the database
  bool stored_in_db{false};
  /// How many non-virtual base columns in base_columns_map
  uint num_non_virtual_base_cols{0};
};
 
class Field {
 public:
  /*
    Field(const Item &) = delete;
    The original intention was seemingly for Field to be non-copyable,
    but due to a typo, this was never enforced, and now there's lots of
    code that copies Field objects around. Thus, the default copy
    constructor needs to stay (assignment is blocked off), but it's probably
    better not to write code that depends on it.
   */
  Field(const Field &) = default;
  void operator=(Field &) = delete;
 
  /**
    Checks if the field is marked as having a general expression to generate
    default values.
 
     @retval true  The field has general expression as default
     @retval false The field doesn't have any general expression as default
  */
  bool has_insert_default_general_value_expression() const {
    return auto_flags & GENERATED_FROM_EXPRESSION;
  }
 
  /**
    Checks if the field is marked as having a datetime value expression to
    generate default values on inserts.
 
    @retval true  The field has datetime expression as default
    @retval false The field doesn't have a datime value expression as default
  */
  bool has_insert_default_datetime_value_expression() const {
    return auto_flags & DEFAULT_NOW;
  }
 
  /**
    Checks if the field is marked as having a datetime value expression to
    generate default values on updates.
 
    @retval true  The field has datetime expression as default for on update
    @retval false The field doesn't have a datime value expression as default
                  for on update
  */
  bool has_update_default_datetime_value_expression() const {
    return auto_flags & ON_UPDATE_NOW;
  }
 
  /**
    Checks if the field is marked as having a constant expression to generate
    default values. Relevant when re-creating a Create_field from a Field
    during ALTER.
 
     @retval true  The field has a constant expression as default
     @retval false The field doesn't have a constant expression as default
  */
  bool has_insert_default_constant_expression() const {
    // For now this is true whenever neither GENERATED_FROM_EXPRESSION nor
    // DEFAULT_NOW is set. If this changes in the future, we can add a separate
    // flag for this.
    return (auto_flags & (GENERATED_FROM_EXPRESSION | DEFAULT_NOW)) == 0;
  }
 
 protected:
  /// Holds the position to the field in record
  uchar *ptr;
 
 private:
  dd::Column::enum_hidden_type m_hidden;
 
  /**
     Byte where the @c NULL bit is stored inside a record. If this Field is a
     @c NOT @c NULL field, this member is @c NULL.
  */
  uchar *m_null_ptr;
 
  /**
    Flag: if the NOT-NULL field can be temporary NULL.
  */
  bool m_is_tmp_nullable;
 
  /**
    This is a flag with the following semantics:
      - it can be changed only when m_is_tmp_nullable is true;
      - it specifies if this field in the first current record
        (TABLE::record[0]) was set to NULL (temporary NULL).
 
    This flag is used for trigger handling.
  */
  bool m_is_tmp_null;
 
  /**
    The value of THD::check_for_truncated_fields at the moment of setting
    m_is_tmp_null attribute.
  */
  enum_check_fields m_check_for_truncated_fields_saved;
 
 protected:
  /*
    null_ptr buffer to be used for Fields that are nullable but
    cannot store null. Typically used from create_tmp_field().
  */
  static uchar dummy_null_buffer;
 
 public:
  uchar *get_null_ptr() { return m_null_ptr; }
  /// Pointer to TABLE object that owns this field
  TABLE *table;
  /// Pointer to original database name, only non-NULL for a temporary table
  const char *orig_db_name{nullptr};
  /// Pointer to original table name, only non-NULL for a temporary table
  const char *orig_table_name{nullptr};
  const char **table_name, *field_name;
  LEX_CSTRING comment;
  /* Field is part of the following keys */
  Key_map key_start;          /* Keys that starts with this field */
  Key_map part_of_key;        ///< Keys that includes this field
                              ///< except of prefix keys.
  Key_map part_of_prefixkey;  ///< Prefix keys
  Key_map part_of_sortkey;    /* ^ but only keys usable for sorting */
  /**
    All keys that include this field, but not extended by the storage engine to
    include primary key columns.
  */
  Key_map part_of_key_not_extended;
 
  /**
    Flags for Field::auto_flags / Create_field::auto_flags bitmaps.
 
    @note NEXT_NUMBER and DEFAULT_NOW/ON_UPDATE_NOW/GENERATED flags should
          never be set at the same time. Also DEFAULT_NOW and GENERATED
          should not be set at the same time.
 
    @warning The values of this enum are used as bit masks for uchar
    Field::auto_flags.
  */
  enum enum_auto_flags {
    NONE = 0,
    NEXT_NUMBER = 1,               ///<  AUTO_INCREMENT
    DEFAULT_NOW = 2,               ///<  DEFAULT CURRENT_TIMESTAMP
    ON_UPDATE_NOW = 4,             ///<  ON UPDATE CURRENT_TIMESTAMP
    GENERATED_FROM_EXPRESSION = 8  ///<  DEFAULT (expression)
  };
 
  enum geometry_type {
    GEOM_GEOMETRY = 0,
    GEOM_POINT = 1,
    GEOM_LINESTRING = 2,
    GEOM_POLYGON = 3,
    GEOM_MULTIPOINT = 4,
    GEOM_MULTILINESTRING = 5,
    GEOM_MULTIPOLYGON = 6,
    GEOM_GEOMETRYCOLLECTION = 7
  };
  enum imagetype { itRAW, itMBR };
 
  // Max width for a VARCHAR column, in number of bytes
  static constexpr size_t MAX_VARCHAR_WIDTH{65535};
 
  // Maximum sizes of the four BLOB types, in number of bytes
  static constexpr size_t MAX_TINY_BLOB_WIDTH{255};
  static constexpr size_t MAX_SHORT_BLOB_WIDTH{65535};
  static constexpr size_t MAX_MEDIUM_BLOB_WIDTH{16777215};
  static constexpr size_t MAX_LONG_BLOB_WIDTH{4294967295};
 
  // Length of field. Never write to this member directly; instead, use
  // set_field_length().
  uint32 field_length;
  virtual void set_field_length(uint32 length) { field_length = length; }
 
  /// Update '*cost' with the fact that this Field is accessed.
  virtual void add_to_cost(CostOfItem *cost) const;
 
 private:
  uint32 flags{0};
  uint16 m_field_index;  // field number in fields array
 
 public:
  bool is_flag_set(unsigned flag) const { return flags & flag; }
  void set_flag(unsigned flag) { flags |= flag; }
  void clear_flag(unsigned flag) { flags &= ~flag; }
  // Avoid using this function as it makes it harder to change the internal
  // representation.
  uint32 all_flags() const { return flags; }
  uchar null_bit;  // Bit used to test null bit
  /**
    Bitmap of flags indicating if field value is auto-generated by default
    and/or on update, and in which way.
 
    @sa Field::enum_auto_flags for possible options.
 
    @sa Field::utype and Field::unireg_check in pre-8.0 versions of server
        for historical perspective.
  */
  uchar auto_flags;
  /**
     If true, this field was created in create_tmp_field_from_item from a NULL
     value. This means that the type of the field is just a guess, and the type
     may be freely coerced to another type.
 
     @see create_tmp_field_from_item
     @see Item_type_holder::get_real_type
 
   */
  bool is_created_from_null_item;
  /**
    If true, it's a Create_field_wrapper (a sub-class of Field used during
    CREATE/ALTER that we mustn't cast to other sub-classes of Field that
    aren't on a direct path of inheritance, e.g. Field_enum).
 
    @see Create_field_wrapper::is_wrapper_field
  */
  virtual bool is_wrapper_field() const { return false; }
 
  /**
     True if this field belongs to some index (unlike part_of_key, the index
     might have only a prefix).
  */
  bool m_indexed;
 
  LEX_CSTRING m_engine_attribute = EMPTY_CSTR;
  LEX_CSTRING m_secondary_engine_attribute = EMPTY_CSTR;
 
 private:
  enum enum_pushed_warnings {
    BAD_NULL_ERROR_PUSHED = 1,
    NO_DEFAULT_FOR_FIELD_PUSHED = 2,
    NO_DEFAULT_FOR_VIEW_FIELD_PUSHED = 4
  };
 
  /*
    Bitmask specifying which warnings have been already pushed in order
    not to repeat the same warning for the collmn multiple times.
    Uses values of enum_pushed_warnings to control pushed warnings.
  */
  unsigned int m_warnings_pushed;
 
 public:
  /* Generated column data */
  Value_generator *gcol_info{nullptr};
  /**
    Indication that the field is physically stored in tables
    rather than just generated on SQL queries.
    As of now, false can only be set for virtual generated columns.
  */
  bool stored_in_db;
  /**
    Whether the field is signed or not. Meaningful only for numeric fields
    and numeric arrays.
  */
  virtual bool is_unsigned() const { return false; }
  bool is_gcol() const { return gcol_info; }
  bool is_virtual_gcol() const { return gcol_info && !stored_in_db; }
 
  /// Holds the expression to be used to generate default values.
  Value_generator *m_default_val_expr{nullptr};
 
  /**
    Sets the hidden type for this field.
 
    @param hidden the new hidden type to set.
  */
  void set_hidden(dd::Column::enum_hidden_type hidden) { m_hidden = hidden; }
 
  /// @returns the hidden type for this field.
  dd::Column::enum_hidden_type hidden() const { return m_hidden; }
 
  /**
    @retval true if this field should be hidden away from users.
    @retval false is this field is visible to the user.
  */
  bool is_hidden() const {
    return hidden() != dd::Column::enum_hidden_type::HT_VISIBLE &&
           DBUG_EVALUATE_IF("show_hidden_columns", false, true);
  }
 
  /**
    @retval true  If this column is hidden either in the storage engine
                  or SQL layer. Either way, it is completely hidden from
                  the user.
    @retval false Otherwise.
  */
  bool is_hidden_by_system() const {
    return (hidden() == dd::Column::enum_hidden_type::HT_HIDDEN_SE ||
            hidden() == dd::Column::enum_hidden_type::HT_HIDDEN_SQL) &&
           DBUG_EVALUATE_IF("show_hidden_columns", false, true);
  }
 
  /**
    @retval true  If this column is hidden by the user.
    @retval false otherwise.
  */
  bool is_hidden_by_user() const {
    return hidden() == dd::Column::enum_hidden_type::HT_HIDDEN_USER;
  }
 
  /**
    @returns true if this is a hidden field that is used for implementing
             functional indexes. Note that if we need different types of hidden
             fields in the future (like invisible columns), this function needs
             to be changed so it can distinguish between the different "types"
             of hidden.
  */
  bool is_field_for_functional_index() const {
    return hidden() == dd::Column::enum_hidden_type::HT_HIDDEN_SQL &&
           gcol_info != nullptr;
  }
 
  Field(uchar *ptr_arg, uint32 length_arg, uchar *null_ptr_arg,
        uchar null_bit_arg, uchar auto_flags_arg, const char *field_name_arg);
 
  virtual ~Field() = default;
 
  void reset_warnings() { m_warnings_pushed = 0; }
 
  /**
    Turn on temporary nullability for the field.
  */
  void set_tmp_nullable() { m_is_tmp_nullable = true; }
 
  /**
    Turn off temporary nullability for the field.
  */
  void reset_tmp_nullable() { m_is_tmp_nullable = false; }
 
  /**
    Reset temporary NULL value for field
  */
  void reset_tmp_null() { m_is_tmp_null = false; }
 
  void set_tmp_null();
 
  /**
    @return temporary NULL-ability flag.
    @retval true if NULL can be assigned temporary to the Field.
    @retval false if NULL can not be assigned even temporary to the Field.
  */
  bool is_tmp_nullable() const { return m_is_tmp_nullable; }
 
  /**
    @return whether Field has temporary value NULL.
    @retval true if the Field has temporary value NULL.
    @retval false if the Field's value is NOT NULL, or if the temporary
    NULL-ability flag is reset.
  */
  bool is_tmp_null() const { return is_tmp_nullable() && m_is_tmp_null; }
 
  /* Store functions returns 1 on overflow and -1 on fatal error */
  virtual type_conversion_status store(const char *to, size_t length,
                                       const CHARSET_INFO *cs) = 0;
  virtual type_conversion_status store(double nr) = 0;
  virtual type_conversion_status store(longlong nr, bool unsigned_val) = 0;
  virtual type_conversion_status store_time(Time_val time, uint8 dec_arg);
 
  /**
    Store a temporal value in packed longlong format into a field.
    The packed value is compatible with TIME_to_longlong_date_packed() or
    TIME_to_longlong_datetime_packed().
    Note, the value must be properly rounded or truncated according
    according to field->decimals().
 
    @param  nr  temporal value in packed longlong format.
    @retval false on success
    @retval true  on error
  */
  virtual type_conversion_status store_packed(longlong nr) {
    return store(nr, false);
  }
  virtual type_conversion_status store_decimal(const my_decimal *d) = 0;
  /**
    Store MYSQL_TIME value with the given amount of decimal digits
    into a field.
 
    Note, the "dec" parameter represents number of digits of the Item
    that previously created the MYSQL_TIME value. It's needed when we
    store the value into a CHAR/VARCHAR/TEXT field to display
    the proper amount of fractional digits.
    For other field types the "dec" value does not matter and is ignored.
 
    @param ltime   Time, date or datetime value.
    @param dec_arg Number of decimals in ltime.
    @retval false  on success
    @retval true   on error
  */
  virtual type_conversion_status store_time(MYSQL_TIME *ltime, uint8 dec_arg);
  /**
    Store MYSQL_TYPE value into a field when the number of fractional
    digits is not important or is not know.
 
    @param ltime   Time, date or datetime value.
    @retval false   on success
    @retval true   on error
  */
  type_conversion_status store_time(MYSQL_TIME *ltime) {
    return store_time(ltime, 0);
  }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *cs,
                               enum_check_fields check_level);
  virtual double val_real() const = 0;
  virtual longlong val_int() const = 0;
  /**
    Returns DATE/DATETIME value in packed longlong format.
    This method should not be called for non-temporal types.
    Temporal field types override the default method.
  */
  virtual longlong val_date_temporal() const {
    assert(0);
    return 0;
  }
 
  virtual longlong val_date_temporal_at_utc() const {
    return val_date_temporal();
  }
 
  virtual my_decimal *val_decimal(my_decimal *) const = 0;
  String *val_str(String *str) const { return val_str(str, str); }
  /*
     val_str(buf1, buf2) gets two buffers and should use them as follows:
     if it needs a temp buffer to convert result to string - use buf1
       example Field_tiny::val_str()
     if the value exists as a string already - use buf2
       example Field_string::val_str()
     consequently, buf2 may be created as 'String buf;' - no memory
     will be allocated for it. buf1 will be allocated to hold a
     value if it's too small. Using allocated buffer for buf2 may result in
     an unnecessary free (and later, may be an alloc).
     This trickery is used to decrease a number of malloc calls.
  */
  virtual String *val_str(String *, String *) const = 0;
  String *val_int_as_str(String *val_buffer, bool unsigned_flag) const;
  /*
   str_needs_quotes() returns true if the value returned by val_str() needs
   to be quoted when used in constructing an SQL query.
  */
  virtual bool str_needs_quotes() const { return false; }
  virtual Item_result result_type() const = 0;
  /**
    Returns Item_result type of a field when it appears
    in numeric context such as:
      SELECT time_column + 1;
      SELECT SUM(time_column);
    Examples:
    - a column of type TIME, DATETIME, TIMESTAMP act as INT.
    - a column of type TIME(1), DATETIME(1), TIMESTAMP(1)
      act as DECIMAL with 1 fractional digits.
  */
  virtual Item_result numeric_context_result_type() const {
    return result_type();
  }
  virtual Item_result cmp_type() const { return result_type(); }
  virtual Item_result cast_to_int_type() const { return result_type(); }
  static bool type_can_have_key_part(enum_field_types);
  static enum_field_types field_type_merge(enum_field_types, enum_field_types);
  static Item_result result_merge_type(enum_field_types);
  bool gcol_expr_is_equal(const Create_field *field) const;
  virtual bool eq(const Field *field) const {
    return (ptr == field->ptr && m_null_ptr == field->m_null_ptr &&
            null_bit == field->null_bit && field->type() == type());
  }
  virtual bool eq_def(const Field *field) const;
 
  /*
    pack_length() returns size (in bytes) used to store field data in memory
    (i.e. it returns the maximum size of the field in a row of the table,
    which is located in RAM).
  */
  virtual uint32 pack_length() const { return (uint32)field_length; }
 
  /*
    pack_length_in_rec() returns size (in bytes) used to store field data on
    storage (i.e. it returns the maximal size of the field in a row of the
    table, which is located on disk).
  */
  virtual uint32 pack_length_in_rec() const { return pack_length(); }
  virtual bool compatible_field_size(uint metadata, Relay_log_info *, uint16,
                                     int *order) const;
  virtual uint pack_length_from_metadata(uint field_metadata) const {
    DBUG_TRACE;
    return field_metadata;
  }
  virtual uint row_pack_length() const { return 0; }
  int save_field_metadata(uchar *first_byte) {
    return do_save_field_metadata(first_byte);
  }
 
  /*
    data_length() return the "real size" of the data in memory.
    Useful only for variable length datatypes where it's overloaded.
    By default assume the length is constant.
  */
  virtual uint32 data_length(ptrdiff_t row_offset [[maybe_unused]] = 0) const {
    return pack_length();
  }
 
  /**
     Get the maximum size of the data in packed format.
 
     @return Maximum data length of the field when packed using the
     Field::pack() function.
   */
  virtual uint32 max_data_length() const { return pack_length(); }
 
  virtual type_conversion_status reset() {
    memset(ptr, 0, pack_length());
    return TYPE_OK;
  }
  /**
    Returns a UTC component in `struct timeval` format. This interface
    makes any column appear to be `TIMESTAMP`, i.e. stored in UTC, and
    returns the UTC component in (optionally fractional) seconds. This means
    converting _to_ UTC from the current session's time zone for types other
    than `TIMESTAMP`.
 
    This method was expressly written for `SELECT UNIX_TIMESTAMP(field)`
    to avoid conversion from timestamp to MYSQL_TIME and back.
  */
  virtual bool get_timestamp(my_timeval *tm, int *warnings) const;
  /**
    Stores a timestamp value in timeval format in a field.
 
   @note
   - store_timestamp(), get_timestamp() and store_time() do not depend on
   timezone and always work "in UTC".
 
   - The default implementation of this interface expects that storing the
   value will not fail. For most Field descendent classes, this is not the
   case. However, this interface is only used when the function
   CURRENT_TIMESTAMP is used as a column default expression, and currently we
   only allow TIMESTAMP and DATETIME columns to be declared with this as the
   column default. Hence it is enough that the classes implementing columns
   with these types either override this interface, or that
   store_time(MYSQL_TIME*, uint8) does not fail.
 
   - The column types above interpret decimals() to mean the scale of the
   fractional seconds.
 
   - We also have the limitation that the scale of a column must be the same as
   the scale of the CURRENT_TIMESTAMP. I.e. we only allow
 
   @code
 
   [ TIMESTAMP | DATETIME ] (n) [ DEFAULT | ON UPDATE ] CURRENT_TIMESTAMP (n)
 
   @endcode
 
   Since this interface relies on the caller to truncate the value according to
   this Field's scale, it will work with all constructs that we currently allow.
  */
  virtual void store_timestamp(const my_timeval *) { assert(false); }
 
  virtual void set_default();
 
  /**
     Evaluates the @c INSERT default function and stores the result in the
     field. If no such function exists for the column, or the function is not
     valid for the column's data type, invoking this function has no effect.
  */
  void evaluate_insert_default_function();
 
  /**
     Evaluates the @c UPDATE default function, if one exists, and stores the
     result in the record buffer. If no such function exists for the column,
     or the function is not valid for the column's data type, invoking this
     function has no effect.
  */
  void evaluate_update_default_function();
  virtual bool binary() const { return true; }
  virtual bool zero_pack() const { return true; }
  virtual enum ha_base_keytype key_type() const { return HA_KEYTYPE_BINARY; }
  virtual uint32 key_length() const { return pack_length(); }
  virtual enum_field_types type() const = 0;
  virtual enum_field_types real_type() const { return type(); }
  virtual enum_field_types binlog_type() const {
    /*
      Binlog stores field->type() as type code by default.
      This puts MYSQL_TYPE_STRING in case of CHAR, VARCHAR, SET and ENUM,
      with extra data type details put into metadata.
 
      We cannot store field->type() in case of temporal types with
      fractional seconds: TIME(n), DATETIME(n) and TIMESTAMP(n),
      because binlog records with MYSQL_TYPE_TIME, MYSQL_TYPE_DATETIME
      type codes do not have metadata.
      So for temporal data types with fractional seconds we'll store
      real_type() type codes instead, i.e.
      MYSQL_TYPE_TIME2, MYSQL_TYPE_DATETIME2, MYSQL_TYPE_TIMESTAMP2,
      and put precision into metatada.
 
      Note: perhaps binlog should eventually be modified to store
      real_type() instead of type() for all column types.
    */
    return type();
  }
  int cmp(const uchar *str) const { return cmp(ptr, str); }
  virtual int cmp_max(const uchar *a, const uchar *b,
                      uint max_len [[maybe_unused]]) const {
    return cmp(a, b);
  }
  virtual int cmp(const uchar *, const uchar *) const = 0;
  virtual int cmp_binary(const uchar *a, const uchar *b,
                         uint32 max_length [[maybe_unused]] = ~0L) const {
    return memcmp(a, b, pack_length());
  }
  virtual int cmp_offset(ptrdiff_t row_offset) const {
    return cmp(ptr, ptr + row_offset);
  }
  virtual int cmp_binary_offset(ptrdiff_t row_offset) const {
    return cmp_binary(ptr, ptr + row_offset);
  }
  virtual int key_cmp(const uchar *a, const uchar *b) const {
    return cmp(a, b);
  }
  virtual int key_cmp(const uchar *str, uint length [[maybe_unused]]) const {
    return cmp(ptr, str);
  }
  virtual uint decimals() const { return 0; }
  virtual bool is_text_key_type() const { return false; }
 
  /*
    Caller beware: sql_type can change str.Ptr, so check
    ptr() to see if it changed if you are using your own buffer
    in str and restore it with set() if needed
  */
  virtual void sql_type(String &str) const = 0;
 
  /**
    Check whether the full table's row is NULL or the Field has value NULL.
 
    @return    true if the full table's row is NULL or the Field has value NULL
               false if neither table's row nor the Field has value NULL
  */
  bool is_null(ptrdiff_t row_offset = 0) const {
    /*
      if the field is NULLable, it returns NULLity based
      on m_null_ptr[row_offset] value. Otherwise it returns
      NULL flag depending on TABLE::has_null_row() value.
 
      The table may have been marked as containing only NULL values
      for all fields if it is a NULL-complemented row of an OUTER JOIN
      or if the query is an implicitly grouped query (has aggregate
      functions but no GROUP BY clause) with no qualifying rows. If
      this is the case (in which TABLE::has_null_row() is true) and the
      field is not nullable, the field is considered to be NULL.
 
      Do not change the order of testing. Fields may be associated
      with a TABLE object without being part of the current row.
      For NULL value check to work for these fields, they must
      have a valid m_null_ptr, and this pointer must be checked before
      TABLE::has_null_row().
    */
    if (is_nullable()) return (m_null_ptr[row_offset] & null_bit);
 
    if (is_tmp_nullable()) return m_is_tmp_null;
 
    return table->has_null_row();
  }
 
  /**
    Check whether the Field has value NULL (temporary or actual).
 
    @return   true if the Field has value NULL (temporary or actual)
              false if the Field has value NOT NULL.
  */
  bool is_real_null(ptrdiff_t row_offset = 0) const {
    if (is_nullable()) return (m_null_ptr[row_offset] & null_bit);
 
    if (is_tmp_nullable()) return m_is_tmp_null;
 
    return false;
  }
 
  /**
    Check if the Field has value NULL or the record specified by argument
    has value NULL for this Field.
 
    @return    true if the Field has value NULL or the record has value NULL
               for thois Field.
  */
  bool is_null_in_record(const uchar *record) const {
    if (is_nullable()) return (record[null_offset()] & null_bit);
 
    return is_tmp_nullable() ? m_is_tmp_null : false;
  }
 
  void set_null(ptrdiff_t row_offset = 0);
 
  void set_notnull(ptrdiff_t row_offset = 0);
 
  // Cannot be const as it calls set_warning
  type_conversion_status check_constraints(int mysql_errno);
 
  /**
    Remember the value of THD::check_for_truncated_fields to handle possible
    NOT-NULL constraint errors after BEFORE-trigger execution is finished.
    We should save the value of THD::check_for_truncated_fields before starting
    BEFORE-trigger processing since during triggers execution the
    value of THD::check_for_truncated_fields could be changed.
  */
  void set_check_for_truncated_fields(
      enum_check_fields check_for_truncated_fields) {
    m_check_for_truncated_fields_saved = check_for_truncated_fields;
  }
 
  /// @return true if this field is NULL-able, false otherwise.
  bool is_nullable() const { return m_null_ptr != nullptr; }
 
  uint null_offset(const uchar *record) const {
    return (uint)(m_null_ptr - record);
  }
 
  uint null_offset() const;
 
  void set_null_ptr(uchar *p_null_ptr, uint p_null_bit) {
    m_null_ptr = p_null_ptr;
    null_bit = p_null_bit;
  }
 
  /**
    Populates a Send_field object with metadata about the column represented by
    this Field object. The Send_field object is used for sending column metadata
    to the client.
 
    @param[out] send_field  the Send_field object to populate
  */
  virtual void make_send_field(Send_field *send_field) const;
 
  /**
    Writes a copy of the current value in the record buffer, suitable for
    sorting using byte-by-byte comparison. Integers are always in big-endian
    regardless of hardware architecture. At most length bytes are written
    into the buffer.
 
    @param buff The buffer, assumed to be at least length bytes.
 
    @param length Number of bytes to write.
 
    @retval The number of bytes actually written.
 
    @note This is now only used by replication; filesort makes its own
     sort keys based off of Items, not Fields.
  */
  virtual size_t make_sort_key(uchar *buff, size_t length) const = 0;
 
  /**
    Writes a copy of the current value in the record buffer, suitable for
    sorting using byte-by-byte comparison. Integers are always in big-endian
    regardless of hardware architecture. At most length bytes are written
    into the buffer. Field_string, Field_varstring and Field_blob classes
    are truncated after pos number of characters.
 
    @param buff The buffer, assumed to be at least length bytes.
 
    @param length Number of bytes to write.
 
    @param trunc_pos Number of characters which should be included before
    truncation.
 
    @retval The number of bytes actually written.
 
    @note This is now only used by replication; filesort makes its own
          sort keys based off of Items, not Fields.
  */
  virtual size_t make_sort_key(uchar *buff, size_t length,
                               size_t trunc_pos [[maybe_unused]]) const {
    return make_sort_key(buff, length);
  }
 
  /**
    Whether this field can be used for index range scans when in
    the given keypart of the given index.
   */
  virtual bool optimize_range(uint idx, uint part) const;
  /*
    This should be true for fields which, when compared with constant
    items, can be casted to longlong. In this case we will at 'fix_fields'
    stage cast the constant items to longlongs and at the execution stage
    use field->val_int() for comparison.  Used to optimize clauses like
    'a_column BETWEEN date_const, date_const'.
  */
  virtual bool can_be_compared_as_longlong() const { return false; }
  virtual void mem_free() {}
 
  virtual Field *new_field(MEM_ROOT *root, TABLE *new_table) const;
 
  Field *new_field(MEM_ROOT *root, TABLE *new_table, uchar *new_ptr,
                   uchar *new_null_ptr, uint new_null_bit) const {
    Field *field = new_field(root, new_table);
    field->move_field(new_ptr, new_null_ptr, new_null_bit);
    return field;
  }
 
  virtual Field *new_key_field(MEM_ROOT *root, TABLE *new_table, uchar *new_ptr,
                               uchar *new_null_ptr, uint new_null_bit) const;
 
  Field *new_key_field(MEM_ROOT *root, TABLE *new_table, uchar *new_ptr) const {
    return new_key_field(root, new_table, new_ptr, m_null_ptr, null_bit);
  }
 
  /**
     Makes a shallow copy of the Field object.
 
     @note This member function must be overridden in all concrete
     subclasses. Several of the Field subclasses are concrete even though they
     are not leaf classes, so the compiler will not always catch this.
 
     @param mem_root MEM_ROOT to use for memory allocation.
     @retval NULL If memory allocation failed.
   */
  virtual Field *clone(MEM_ROOT *mem_root) const = 0;
 
  void move_field(uchar *ptr_arg, uchar *null_ptr_arg, uchar null_bit_arg) {
    ptr = ptr_arg;
    m_null_ptr = null_ptr_arg;
    null_bit = null_bit_arg;
  }
 
  virtual void move_field_offset(ptrdiff_t ptr_diff) {
    ptr += ptr_diff;
    if (is_nullable()) m_null_ptr += ptr_diff;
  }
 
  virtual void get_image(uchar *buff, size_t length,
                         const CHARSET_INFO *) const {
    memcpy(buff, ptr, length);
  }
 
  virtual void set_image(const uchar *buff, size_t length,
                         const CHARSET_INFO *) {
    memcpy(ptr, buff, length);
  }
 
  /*
    Copy a field part into an output buffer.
 
    SYNOPSIS
      Field::get_key_image()
      buff   [out] output buffer
      length       output buffer size
      type         itMBR for geometry blobs, otherwise itRAW
 
    DESCRIPTION
      This function makes a copy of field part of size equal to or
      less than "length" parameter value.
      For fields of string types (CHAR, VARCHAR, TEXT) the rest of buffer
      is padded by zero byte.
 
    NOTES
      For variable length character fields (i.e. UTF-8) the "length"
      parameter means a number of output buffer bytes as if all field
      characters have maximal possible size (mbmaxlen). In the other words,
      "length" parameter is a number of characters multiplied by
      field_charset->mbmaxlen.
 
    RETURN
      Number of copied bytes (excluding padded zero bytes -- see above).
  */
 
  virtual size_t get_key_image(uchar *buff, size_t length,
                               imagetype type [[maybe_unused]]) const {
    get_image(buff, length, &my_charset_bin);
    return length;
  }
  virtual void set_key_image(const uchar *buff, size_t length) {
    set_image(buff, length, &my_charset_bin);
  }
  longlong val_int_offset(ptrdiff_t row_offset) {
    ptr += row_offset;
    const longlong tmp = val_int();
    ptr -= row_offset;
    return tmp;
  }
  longlong val_int(uchar *new_ptr) {
    uchar *old_ptr = ptr;
    longlong return_value;
    ptr = new_ptr;
    return_value = val_int();
    ptr = old_ptr;
    return return_value;
  }
  String *val_str(String *str, uchar *new_ptr) {
    uchar *old_ptr = ptr;
    ptr = new_ptr;
    val_str(str);
    ptr = old_ptr;
    return str;
  }
 
  /**
    Send the value of this field over the protocol using the correct
    Protocol::store*() function which matches the type of the field.
  */
  virtual bool send_to_protocol(Protocol *protocol) const;
 
  /**
    Pack the field into a format suitable for storage and transfer.
 
    To implement packing functionality, only the virtual function
    should be overridden. The other functions are just convenience
    functions and hence should not be overridden.
 
    The actual format is opaque and will vary between types of Field
    (it is meant to be unpacked by unpack(), but be aware that it is
    used among others in the replication log, so you cannot change it
    without incurring a format break.
 
    @note The default implementation just copies the raw bytes
      of the record into the destination, but never more than
      <code>max_length</code> characters.
 
    @param to
      Pointer to memory area where representation of field should be put.
 
    @param from
      Pointer to memory area where record representation of field is
      stored, typically field->field_ptr().
 
    @param max_length
      Available space in “to”, in bytes. pack() will not write more bytes than
      this; if the field is too short, the contents _are not unpackable by
      unpack()_. (It is nominally supposed to be a prefix of what would have
      been written with a full buffer, ie., the same as packing and then
      truncating the output, but not all Field classes follow this.)
 
    @return The byte after the last byte in “to” written to. If the return
      value is equal to (to + max_length), it could either be that the value
      fit exactly, or that the buffer was too small; you cannot distinguish
      between the two cases based on the return value alone.
   */
  virtual uchar *pack(uchar *to, const uchar *from, size_t max_length) const;
 
  uchar *pack(uchar *to) const { return pack(to, ptr, UINT_MAX); }
 
  virtual const uchar *unpack(uchar *to, const uchar *from, uint param_data);
 
  const uchar *unpack(const uchar *from) { return unpack(ptr, from, 0U); }
 
  /**
    This function does the same thing as pack(), except for the difference
    that max_length does not mean the number of bytes in the output, but the
    maximum field length from the input (which must be exactly
    field->max_field_length()). The difference is currently only relevant for
    Field_blob, but can be summed up as follows:
 
     - If the actual field length is longer than "max_length", by way of
       software bug or otherwise, the function may behave as if it were shorter,
       and write something that is still readable by unpack().
     - There is no bounds checking; the caller must verify that there is
       sufficient space in "to". Even in the case of truncation, "to" must
       be long enough to hold the untruncated field, as the return pointer
       would otherwise be invalid, causing undefined behavior as per the C++
       standard.
   */
  virtual uchar *pack_with_metadata_bytes(uchar *to, const uchar *from,
                                          uint max_length) const {
    return pack(to, from, max_length);
  }
 
  /**
    Write the field for the binary log in diff format.
 
    This should only write the field if the diff format is smaller
    than the full format.  Otherwise it should leave the buffer
    untouched.
 
    @param[in,out] to Pointer to buffer where the field will be
    written.  This will be changed to point to the next byte after the
    last byte that was written.
 
    @param value_options bitmap that indicates if full or partial
    JSON format is to be used.
 
    @retval true The field was not written, either because the data
    type does not support it, or because it was disabled according to
    value_options, or because there was no diff information available
    from the optimizer, or because the the diff format was bigger than
    the full format.  The 'to' parameter is unchanged in this case.
 
    @retval false The field was written.
  */
  virtual bool pack_diff(uchar **to [[maybe_unused]],
                         ulonglong value_options [[maybe_unused]]) const {
    return true;
  }
 
  /**
    This is a wrapper around pack_length() used by filesort() to determine
    how many bytes we need for packing "addon fields".
    @returns maximum size of a row when stored in the filesort buffer.
   */
 
  virtual uint max_packed_col_length() const { return pack_length(); }
 
  uint offset(uchar *record) const { return (uint)(ptr - record); }
 
  void copy_data(ptrdiff_t src_record_offset);
 
  virtual bool val_date(Date_val *date, my_time_flags_t flags) const;
 
  virtual bool val_time(Time_val *time) const;
 
  virtual bool val_datetime(Datetime_val *dt, my_time_flags_t flags) const;
 
  virtual const CHARSET_INFO *charset() const { return &my_charset_bin; }
 
  const CHARSET_INFO *charset_for_protocol() const {
    return binary() ? &my_charset_bin : charset();
  }
  virtual const CHARSET_INFO *sort_charset() const { return charset(); }
  virtual bool has_charset() const { return false; }
  /*
    match_collation_to_optimize_range() is to distinguish in
    range optimizer (see opt_range.cc) between real string types:
      CHAR, VARCHAR, TEXT
    and the other string-alike types with result_type() == STRING_RESULT:
      DATE, TIME, DATETIME, TIMESTAMP
    We need it to decide whether to test if collation of the operation
    matches collation of the field (needed only for real string types).
    QQ: shouldn't DATE/TIME types have their own XXX_RESULT types eventually?
  */
 
  virtual bool match_collation_to_optimize_range() const { return false; }
  virtual enum Derivation derivation() const { return DERIVATION_IMPLICIT; }
  virtual uint repertoire() const { return MY_REPERTOIRE_UNICODE30; }
  virtual void set_derivation(enum Derivation) {}
 
  /**
    Produce warning or note about data saved into field.
 
    @param level            - level of message (Note/Warning/Error)
    @param code             - error code of message to be produced
    @param cut_increment    - whenever we should increase cut fields count
 
    @note
      This function won't produce warning and increase cut fields counter
      if check_for_truncated_fields == CHECK_FIELD_IGNORE for current thread.
 
      if check_for_truncated_fields == CHECK_FIELD_IGNORE then we ignore notes.
      This allows us to avoid notes in optimization, like
      convert_constant_item().
 
    @retval
      1 if check_for_truncated_fields == CHECK_FIELD_IGNORE and error level
      is not NOTE
    @retval
      0 otherwise
  */
  bool set_warning(Sql_condition::enum_severity_level level, unsigned int code,
                   int cut_increment) {
    return set_warning(level, code, cut_increment, nullptr, nullptr);
  }
 
  bool set_warning(Sql_condition::enum_severity_level level, uint code,
                   int cut_increment, const char *view_db,
                   const char *view_name);
 
  bool warn_if_overflow(int op_result);
  virtual void init(TABLE *table_arg);
 
  /* maximum possible display length */
  virtual uint32 max_display_length() const = 0;
 
  /**
    Whether a field being created is type-compatible with an existing one.
 
    Used by the ALTER TABLE code to evaluate whether the new definition
    of a table is compatible with the old definition so that it can
    determine if data needs to be copied over (table data change).
    Constraints and generation clause (default value, generation expression)
    are not checked by this function.
 
    @param new_field new field definition from alter.
    @retval IS_EQUAL_YES if there is no change.
    @retval IS_EQUAL_PACK_LENGTH if the data are unchanged, but the length
    requirements have changed
    @retval IS_EQUAL_NO if there is an incompatible change requiring copy.
  */
 
  virtual uint is_equal(const Create_field *new_field) const;
 
  /* convert decimal to longlong with overflow check */
  longlong convert_decimal2longlong(const my_decimal *val, bool unsigned_flag,
                                    bool *has_overflow);
  /* The max. number of characters */
  virtual uint32 char_length() const {
    return field_length / charset()->mbmaxlen;
  }
 
  virtual geometry_type get_geometry_type() const {
    /* shouldn't get here. */
    assert(0);
    return GEOM_GEOMETRY;
  }
#ifndef NDEBUG
  /* Print field value into debug trace, in NULL-aware way. */
  void dbug_print() const {
    if (is_real_null())
      fprintf(DBUG_FILE, "NULL");
    else {
      char buf[256];
      String str(buf, sizeof(buf), &my_charset_bin);
      str.length(0);
      String *pstr;
      pstr = val_str(&str);
      fprintf(DBUG_FILE, "'%s'", pstr->c_ptr_safe());
    }
  }
#endif
 
  ha_storage_media field_storage_type() const {
    return (ha_storage_media)((flags >> FIELD_FLAGS_STORAGE_MEDIA) & 3);
  }
 
  void set_storage_type(ha_storage_media storage_type_arg) {
    assert(field_storage_type() == HA_SM_DEFAULT);
    flags |= (storage_type_arg << FIELD_FLAGS_STORAGE_MEDIA);
  }
 
  column_format_type column_format() const {
    return (column_format_type)((flags >> FIELD_FLAGS_COLUMN_FORMAT) & 3);
  }
 
  void set_column_format(column_format_type column_format_arg) {
    assert(column_format() == COLUMN_FORMAT_TYPE_DEFAULT);
    flags |= (column_format_arg << FIELD_FLAGS_COLUMN_FORMAT);
  }
 
  /* Validate the value stored in a field */
  virtual type_conversion_status validate_stored_val(THD *thd
                                                     [[maybe_unused]]) {
    return TYPE_OK;
  }
 
  /* Hash value */
  virtual void hash(ulong *nr, ulong *nr2) const;
 
  /**
    Get the upper limit of the MySQL integral and floating-point type.
 
    @return maximum allowed value for the field
  */
  virtual ulonglong get_max_int_value() const {
    assert(false);
    return 0ULL;
  }
 
  /**
    Return a const pointer to the actual data in the record buffer.
 
    For most fields, this is the same as field_ptr(), but BLOBs and VARCHARs
    it is not. Ideally this function should not be used as it makes it hard
    to change the internal representation of Field.
  */
  virtual const uchar *data_ptr() const { return ptr; }
 
  /**
    Return a const pointer to where the field is stored in the record buffer.
 
    Ideally this function should not be used as it makes it hard
    to change the internal representation of Field.
  */
  const uchar *field_ptr() const { return ptr; }
 
  /**
    Return a pointer to where the field is stored in the record buffer.
 
    Ideally this function should not be used as it makes it hard
    to change the internal representation of Field.
  */
  uchar *field_ptr() { return ptr; }
 
  void set_field_ptr(uchar *ptr_arg) { ptr = ptr_arg; }
 
  /**
    Checks whether a string field is part of write_set.
 
    @return
      false  - If field is not char/varchar/....
             - If field is char/varchar/.. and is not part of write set.
      true   - If field is char/varchar/.. and is part of write set.
  */
  virtual bool is_updatable() const { return false; }
 
  /**
    Check whether field is part of the index taking the index extensions flag
    into account. Index extensions are also not applicable to UNIQUE indexes
    for loose index scans.
 
    @param[in]     thd             THD object
    @param[in]     cur_index       Index of the key
    @param[in]     cur_index_info  key_info object
 
    @retval true  Field is part of the key
    @retval false otherwise
 
  */
 
  bool is_part_of_actual_key(THD *thd, uint cur_index,
                             KEY *cur_index_info) const;
 
  /**
    Get covering prefix keys.
 
    @retval covering prefix keys.
  */
  Key_map get_covering_prefix_keys() const;
 
  /// Whether the field is a typed array
  virtual bool is_array() const { return false; }
 
  /**
    Return number of bytes the field's length takes
 
    Valid only for varchar and typed arrays of varchar
  */
  virtual uint32 get_length_bytes() const {
    assert(0);
    return 0;
  }
 
  /**
    Whether field's old valued have to be handled.
 
    @returns
      true   if field is virtual an either one of BLOB types or typed array
      false  otherwise
  */
  bool handle_old_value() const {
    return (is_flag_set(BLOB_FLAG) || is_array()) && is_virtual_gcol();
  }
 
  /**
    Sets field index.
 
    @param[in]  field_index  Field index.
  */
  virtual void set_field_index(uint16 field_index) {
    m_field_index = field_index;
  }
 
  /**
    Returns field index.
 
    @returns Field index.
  */
  uint16 field_index() const { return m_field_index; }
 
 private:
  /**
     Retrieve the field metadata for fields.
 
     This default implementation returns 0 and saves 0 in the metadata_ptr
     value.
 
     @param   metadata_ptr   First byte of field metadata
 
     @returns 0 no bytes written.
  */
  virtual int do_save_field_metadata(uchar *metadata_ptr
                                     [[maybe_unused]]) const {
    return 0;
  }
 
 protected:
  uchar *pack_int16(uchar *to, const uchar *from, size_t max_length) const;
 
  const uchar *unpack_int16(uchar *to, const uchar *from) const;
 
  uchar *pack_int24(uchar *to, const uchar *from, size_t max_length) const;
 
  const uchar *unpack_int24(uchar *to, const uchar *from) const;
 
  uchar *pack_int32(uchar *to, const uchar *from, size_t max_length) const;
 
  const uchar *unpack_int32(uchar *to, const uchar *from) const;
 
  uchar *pack_int64(uchar *to, const uchar *from, size_t max_length) const;
 
  const uchar *unpack_int64(uchar *to, const uchar *from) const;
};
 
/**
  This class is a substitute for the Field classes during CREATE TABLE
 
  When adding a functional index at table creation, we need to resolve the
  expression we are indexing. All functions that references one or more
  columns expect a Field to be available. But during CREATE TABLE, we only
  have access to Create_field. So this class acts as a substitute for the
  Field classes so that expressions can be properly resolved. Thus, trying
  to call store or val_* on this class will cause an assertion.
*/
class Create_field_wrapper final : public Field {
  const Create_field *m_field;
 
 public:
  Create_field_wrapper(const Create_field *fld);
  Item_result result_type() const final;
  Item_result numeric_context_result_type() const final;
  enum_field_types type() const final;
  uint32 max_display_length() const final;
 
  const CHARSET_INFO *charset() const final;
 
  uint32 pack_length() const final;
 
  // Since it's not a real field, functions below shouldn't be used.
  /* purecov: begin deadcode */
  type_conversion_status store(const char *, size_t,
                               const CHARSET_INFO *) final {
    assert(false);
    return TYPE_ERR_BAD_VALUE;
  }
  type_conversion_status store(double) final {
    assert(false);
    return TYPE_ERR_BAD_VALUE;
  }
  type_conversion_status store(longlong, bool) final {
    assert(false);
    return TYPE_ERR_BAD_VALUE;
  }
  type_conversion_status store_decimal(const my_decimal *) final {
    assert(false);
    return TYPE_ERR_BAD_VALUE;
  }
  type_conversion_status store_time(Time_val, uint8) final {
    assert(false);
    return TYPE_ERR_BAD_VALUE;
  }
  type_conversion_status store_time(MYSQL_TIME *, uint8) final {
    assert(false);
    return TYPE_ERR_BAD_VALUE;
  }
  double val_real(void) const final {
    assert(false);
    return 0.0;
  }
  longlong val_int(void) const final {
    assert(false);
    return 0;
  }
  my_decimal *val_decimal(my_decimal *) const final {
    assert(false);
    return nullptr;
  }
  String *val_str(String *, String *) const final {
    assert(false);
    return nullptr;
  }
  int cmp(const uchar *, const uchar *) const final {
    assert(false);
    return -1;
  }
  void sql_type(String &) const final { assert(false); }
  using Field::make_sort_key;
  size_t make_sort_key(uchar *, size_t) const final {
    assert(false);
    return 0;
  }
  Field *clone(MEM_ROOT *mem_root) const final {
    return new (mem_root) Create_field_wrapper(*this);
  }
  bool is_wrapper_field() const final { return true; }
  /* purecov: end */
};
 
class Field_num : public Field {
 private:
  /**
    Whether the field is signed or not. Meaningful only for numeric fields
    and numeric arrays.
  */
  const bool unsigned_flag;
 
 public:
  const uint8 dec;
  /**
    True if the column was declared with the ZEROFILL attribute. If it has the
    attribute, values should be zero-padded up to the declared display width
    when they are converted to strings.
  */
  bool zerofill;  // Purify cannot handle bit fields
  Field_num(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
            uchar null_bit_arg, uchar auto_flags_arg,
            const char *field_name_arg, uint8 dec_arg, bool zero_arg,
            bool unsigned_arg);
  bool is_unsigned() const final { return unsigned_flag; }
  Item_result result_type() const override { return REAL_RESULT; }
  enum Derivation derivation() const final { return DERIVATION_NUMERIC; }
  uint repertoire() const final { return MY_REPERTOIRE_NUMERIC; }
  const CHARSET_INFO *charset() const final { return &my_charset_numeric; }
  void prepend_zeros(String *value) const;
  uint decimals() const final { return (uint)dec; }
  bool eq_def(const Field *field) const final;
  type_conversion_status store_decimal(const my_decimal *) override;
  type_conversion_status store_time(Time_val time, uint8 dec_arg) override;
  type_conversion_status store_time(MYSQL_TIME *ltime, uint8 dec) override;
  my_decimal *val_decimal(my_decimal *) const override;
  bool val_date(Date_val *date, my_time_flags_t flags) const override;
  bool val_time(Time_val *time) const override;
  bool val_datetime(Datetime_val *dt, my_time_flags_t flags) const override;
  uint is_equal(const Create_field *new_field) const override;
  uint row_pack_length() const final { return pack_length(); }
  uint32 pack_length_from_metadata(uint) const override {
    return pack_length();
  }
  type_conversion_status check_int(const CHARSET_INFO *cs, const char *str,
                                   size_t length, const char *int_end,
                                   int error);
  type_conversion_status get_int(const CHARSET_INFO *cs, const char *from,
                                 size_t len, longlong *rnd,
                                 ulonglong unsigned_max, longlong signed_min,
                                 longlong signed_max);
};
 
class Field_str : public Field {
 protected:
  const CHARSET_INFO *field_charset;
  enum Derivation field_derivation;
 
 public:
  Field_str(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
            uchar null_bit_arg, uchar auto_flags_arg,
            const char *field_name_arg, const CHARSET_INFO *charset);
  Item_result result_type() const override { return STRING_RESULT; }
  Item_result numeric_context_result_type() const final { return REAL_RESULT; }
  uint decimals() const override { return DECIMAL_NOT_SPECIFIED; }
  void make_send_field(Send_field *field) const override;
  type_conversion_status store(double nr) override;
  type_conversion_status store(longlong nr, bool unsigned_val) override = 0;
  type_conversion_status store_decimal(const my_decimal *) override;
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *cs) override = 0;
 
  uint repertoire() const final { return my_charset_repertoire(field_charset); }
  const CHARSET_INFO *charset() const override { return field_charset; }
  void set_charset(const CHARSET_INFO *charset_arg) {
    field_charset = charset_arg;
    char_length_cache = char_length();
  }
  void set_field_length(uint32 length) final {
    Field::set_field_length(length);
    char_length_cache = char_length();
  }
  enum Derivation derivation() const final { return field_derivation; }
  void set_derivation(enum Derivation derivation_arg) final {
    field_derivation = derivation_arg;
  }
  bool binary() const override { return field_charset == &my_charset_bin; }
  uint32 max_display_length() const override { return field_length; }
  bool str_needs_quotes() const final { return true; }
  uint is_equal(const Create_field *new_field) const override;
 
  void add_to_cost(CostOfItem *cost) const override;
 
  // An always-updated cache of the result of char_length(), because
  // dividing by charset()->mbmaxlen can be surprisingly costly compared
  // to the rest of e.g. make_sort_key().
  uint32 char_length_cache;
};
 
/* base class for Field_string, Field_varstring and Field_blob */
 
class Field_longstr : public Field_str {
 private:
  type_conversion_status report_if_important_data(const char *ptr,
                                                  const char *end,
                                                  bool count_spaces);
 
 protected:
  type_conversion_status check_string_copy_error(
      const char *well_formed_error_pos, const char *cannot_convert_error_pos,
      const char *from_end_pos, const char *end, bool count_spaces,
      const CHARSET_INFO *from_cs, const CHARSET_INFO *to_cs);
 
 public:
  Field_longstr(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
                uchar null_bit_arg, uchar auto_flags_arg,
                const char *field_name_arg, const CHARSET_INFO *charset_arg)
      : Field_str(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                  field_name_arg, charset_arg) {}
 
  type_conversion_status store_decimal(const my_decimal *d) override;
  uint32 max_data_length() const override;
  bool is_updatable() const final;
};
 
/* base class for float and double and decimal (old one) */
class Field_real : public Field_num {
 public:
  bool not_fixed;
  enum Truncate_result {
    TR_OK = 0,
    TR_POSITIVE_OVERFLOW = 1,
    TR_NEGATIVE_OVERFLOW = 2
  };
 
  Field_real(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
             uchar null_bit_arg, uchar auto_flags_arg,
             const char *field_name_arg, uint8 dec_arg, bool zero_arg,
             bool unsigned_arg)
      : Field_num(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                  field_name_arg, dec_arg, zero_arg, unsigned_arg),
        not_fixed(dec_arg >= DECIMAL_NOT_SPECIFIED) {}
  type_conversion_status store_time(Time_val time, uint8 dec_arg) final;
  type_conversion_status store_decimal(const my_decimal *) final;
  type_conversion_status store_time(MYSQL_TIME *ltime, uint8 dec) final;
  my_decimal *val_decimal(my_decimal *) const final;
  bool val_date(Date_val *date, my_time_flags_t flags) const final;
  bool val_time(Time_val *time) const final;
  bool val_datetime(Datetime_val *dt, my_time_flags_t flags) const override;
  Truncate_result truncate(double *nr, double max_length);
  Truncate_result truncate(double *nr, double max_length) const;
  uint32 max_display_length() const final { return field_length; }
  const uchar *unpack(uchar *to, const uchar *from, uint param_data) override;
  uchar *pack(uchar *to, const uchar *from, size_t max_length) const override;
};
 
class Field_decimal final : public Field_real {
 public:
  Field_decimal(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
                uchar null_bit_arg, uchar auto_flags_arg,
                const char *field_name_arg, uint8 dec_arg, bool zero_arg,
                bool unsigned_arg)
      : Field_real(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                   field_name_arg, dec_arg, zero_arg, unsigned_arg) {}
  enum_field_types type() const final { return MYSQL_TYPE_DECIMAL; }
  enum ha_base_keytype key_type() const final {
    return zerofill ? HA_KEYTYPE_BINARY : HA_KEYTYPE_NUM;
  }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  double val_real() const final;
  longlong val_int() const final;
  String *val_str(String *, String *) const final;
  int cmp(const uchar *, const uchar *) const final;
  using Field_real::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  void overflow(bool negative);
  bool zero_pack() const final { return false; }
  void sql_type(String &str) const final;
  Field_decimal *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_DECIMAL);
    return new (mem_root) Field_decimal(*this);
  }
  const uchar *unpack(uchar *to, const uchar *from, uint param_data) final {
    return Field::unpack(to, from, param_data);
  }
  uchar *pack(uchar *to, const uchar *from, size_t max_length) const final {
    return Field::pack(to, from, max_length);
  }
};
 
/* New decimal/numeric field which use fixed point arithmetic */
class Field_new_decimal : public Field_num {
 private:
  /**
    Normally, the underlying decimal code will degrade values' excessive
    precision.  E.g. value 0.0 stored as decimal(10,4) will be returned as
    decimal(4,4). This is fine for general purpose, but isn't usable for
    multi-valued index. Field_typed_array uses a field for conversion and it
    expects the value read from it to be exactly same as it would be stored
    in SE, i.e with preserved precision. Otherwise, SE won't be able to
    index it.
    TRUE here tells underlying DECIMAL reading code to keep the precision as
    is.
  */
  bool m_keep_precision{false};
  int do_save_field_metadata(uchar *first_byte) const final;
 
 public:
  /* The maximum number of decimal digits can be stored */
  uint precision;
  uint bin_size;
  /*
    Constructors take max_length of the field as a parameter - not the
    precision as the number of decimal digits allowed.
    So for example we need to count length from precision handling
    CREATE TABLE ( DECIMAL(x,y))
  */
  Field_new_decimal(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
                    uchar null_bit_arg, uchar auto_flags_arg,
                    const char *field_name_arg, uint8 dec_arg, bool zero_arg,
                    bool unsigned_arg);
  Field_new_decimal(uint32 len_arg, bool is_nullable_arg,
                    const char *field_name_arg, uint8 dec_arg,
                    bool unsigned_arg);
  enum_field_types type() const final { return MYSQL_TYPE_NEWDECIMAL; }
  enum ha_base_keytype key_type() const final { return HA_KEYTYPE_BINARY; }
  Item_result result_type() const final { return DECIMAL_RESULT; }
  type_conversion_status reset() final;
  type_conversion_status store_value(const my_decimal *decimal_value);
  void set_value_on_overflow(my_decimal *decimal_value, bool sign) const;
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  type_conversion_status store_time(Time_val time, uint8 dec_arg) final;
  type_conversion_status store_time(MYSQL_TIME *ltime, uint8 dec) final;
  type_conversion_status store_decimal(const my_decimal *) final;
  double val_real() const final;
  longlong val_int() const final;
  my_decimal *val_decimal(my_decimal *) const final;
  bool val_date(Date_val *date, my_time_flags_t flags) const final;
  bool val_time(Time_val *time) const final;
  bool val_datetime(Datetime_val *dt, my_time_flags_t flags) const final;
  String *val_str(String *, String *) const final;
  int cmp(const uchar *, const uchar *) const final;
  using Field_num::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  bool zero_pack() const final { return false; }
  void sql_type(String &str) const final;
  uint32 max_display_length() const final { return field_length; }
  uint32 pack_length() const final { return (uint32)bin_size; }
  uint pack_length_from_metadata(uint field_metadata) const final;
  bool compatible_field_size(uint field_metadata, Relay_log_info *, uint16,
                             int *order_var) const final;
  uint is_equal(const Create_field *new_field) const final;
  Field_new_decimal *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_NEWDECIMAL);
    return new (mem_root) Field_new_decimal(*this);
  }
  const uchar *unpack(uchar *to, const uchar *from, uint param_data) final;
  static Field *create_from_item(const Item *item);
  bool send_to_protocol(Protocol *protocol) const final;
  void set_keep_precision(bool arg) { m_keep_precision = arg; }
};
 
class Field_tiny : public Field_num {
 public:
  Field_tiny(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
             uchar null_bit_arg, uchar auto_flags_arg,
             const char *field_name_arg, bool zero_arg, bool unsigned_arg)
      : Field_num(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                  field_name_arg, 0, zero_arg, unsigned_arg) {}
  Field_tiny(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
             bool unsigned_arg)
      : Field_num(nullptr, len_arg,
                  is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                  field_name_arg, 0, false, unsigned_arg) {}
  enum Item_result result_type() const final { return INT_RESULT; }
  enum_field_types type() const override { return MYSQL_TYPE_TINY; }
  enum ha_base_keytype key_type() const final {
    return is_unsigned() ? HA_KEYTYPE_BINARY : HA_KEYTYPE_INT8;
  }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) override;
  type_conversion_status store(double nr) override;
  type_conversion_status store(longlong nr, bool unsigned_val) override;
  double val_real() const override;
  longlong val_int() const override;
  String *val_str(String *, String *) const override;
  bool send_to_protocol(Protocol *protocol) const override;
  int cmp(const uchar *, const uchar *) const final;
  using Field_num::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  uint32 pack_length() const final { return 1; }
  void sql_type(String &str) const override;
  uint32 max_display_length() const final { return 4; }
  Field_tiny *clone(MEM_ROOT *mem_root) const override {
    assert(type() == MYSQL_TYPE_TINY);
    return new (mem_root) Field_tiny(*this);
  }
  uchar *pack(uchar *to, const uchar *from, size_t max_length) const final {
    if (max_length > 0) *to = *from;
    return to + 1;
  }
 
  const uchar *unpack(uchar *to, const uchar *from,
                      uint param_data [[maybe_unused]]) final {
    *to = *from;
    return from + 1;
  }
 
  ulonglong get_max_int_value() const final {
    return is_unsigned() ? 0xFFULL : 0x7FULL;
  }
};
 
class Field_short final : public Field_num {
 public:
  Field_short(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
              uchar null_bit_arg, uchar auto_flags_arg,
              const char *field_name_arg, bool zero_arg, bool unsigned_arg)
      : Field_num(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                  field_name_arg, 0, zero_arg, unsigned_arg) {}
  Field_short(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
              bool unsigned_arg)
      : Field_num(nullptr, len_arg,
                  is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                  field_name_arg, 0, false, unsigned_arg) {}
  Field_short(uint32 len_arg, const char *field_name_arg, bool unsigned_arg)
      : Field_short(len_arg, false, field_name_arg, unsigned_arg) {}
  enum Item_result result_type() const final { return INT_RESULT; }
  enum_field_types type() const final { return MYSQL_TYPE_SHORT; }
  enum ha_base_keytype key_type() const final {
    return is_unsigned() ? HA_KEYTYPE_USHORT_INT : HA_KEYTYPE_SHORT_INT;
  }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  double val_real() const final;
  longlong val_int() const final;
  String *val_str(String *, String *) const final;
  bool send_to_protocol(Protocol *protocol) const final;
  int cmp(const uchar *, const uchar *) const final;
  using Field_num::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  uint32 pack_length() const final { return 2; }
  void sql_type(String &str) const final;
  uint32 max_display_length() const final { return 6; }
  Field_short *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_SHORT);
    return new (mem_root) Field_short(*this);
  }
  uchar *pack(uchar *to, const uchar *from, size_t max_length) const final {
    return pack_int16(to, from, max_length);
  }
 
  const uchar *unpack(uchar *to, const uchar *from,
                      uint param_data [[maybe_unused]]) final {
    return unpack_int16(to, from);
  }
 
  ulonglong get_max_int_value() const final {
    return is_unsigned() ? 0xFFFFULL : 0x7FFFULL;
  }
};
 
class Field_medium final : public Field_num {
 public:
  Field_medium(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
               uchar null_bit_arg, uchar auto_flags_arg,
               const char *field_name_arg, bool zero_arg, bool unsigned_arg)
      : Field_num(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                  field_name_arg, 0, zero_arg, unsigned_arg) {}
  Field_medium(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
               bool unsigned_arg)
      : Field_num(nullptr, len_arg,
                  is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                  field_name_arg, 0, false, unsigned_arg) {}
  enum Item_result result_type() const final { return INT_RESULT; }
  enum_field_types type() const final { return MYSQL_TYPE_INT24; }
  enum ha_base_keytype key_type() const final {
    return is_unsigned() ? HA_KEYTYPE_UINT24 : HA_KEYTYPE_INT24;
  }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  double val_real() const final;
  longlong val_int() const final;
  String *val_str(String *, String *) const final;
  bool send_to_protocol(Protocol *protocol) const final;
  int cmp(const uchar *, const uchar *) const final;
  using Field_num::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  uint32 pack_length() const final { return 3; }
  void sql_type(String &str) const final;
  uint32 max_display_length() const final { return 8; }
  Field_medium *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_INT24);
    return new (mem_root) Field_medium(*this);
  }
  ulonglong get_max_int_value() const final {
    return is_unsigned() ? 0xFFFFFFULL : 0x7FFFFFULL;
  }
};
 
class Field_long : public Field_num {
 public:
  static const int PACK_LENGTH = 4;
 
  Field_long(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
             uchar null_bit_arg, uchar auto_flags_arg,
             const char *field_name_arg, bool zero_arg, bool unsigned_arg)
      : Field_num(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                  field_name_arg, 0, zero_arg, unsigned_arg) {}
  Field_long(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
             bool unsigned_arg)
      : Field_num(nullptr, len_arg,
                  is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                  field_name_arg, 0, false, unsigned_arg) {}
  enum Item_result result_type() const final { return INT_RESULT; }
  enum_field_types type() const final { return MYSQL_TYPE_LONG; }
  enum ha_base_keytype key_type() const final {
    return is_unsigned() ? HA_KEYTYPE_ULONG_INT : HA_KEYTYPE_LONG_INT;
  }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) override;
  double val_real() const final;
  longlong val_int() const final;
  bool send_to_protocol(Protocol *protocol) const final;
  String *val_str(String *, String *) const final;
  int cmp(const uchar *, const uchar *) const final;
  using Field_num::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  uint32 pack_length() const final { return PACK_LENGTH; }
  void sql_type(String &str) const final;
  uint32 max_display_length() const final {
    return MY_INT32_NUM_DECIMAL_DIGITS;
  }
  Field_long *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_LONG);
    return new (mem_root) Field_long(*this);
  }
  uchar *pack(uchar *to, const uchar *from, size_t max_length) const final {
    return pack_int32(to, from, max_length);
  }
  const uchar *unpack(uchar *to, const uchar *from,
                      uint param_data [[maybe_unused]]) final {
    return unpack_int32(to, from);
  }
 
  ulonglong get_max_int_value() const final {
    return is_unsigned() ? 0xFFFFFFFFULL : 0x7FFFFFFFULL;
  }
};
 
class Field_longlong : public Field_num {
 public:
  static const int PACK_LENGTH = 8;
 
  Field_longlong(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
                 uchar null_bit_arg, uchar auto_flags_arg,
                 const char *field_name_arg, bool zero_arg, bool unsigned_arg)
      : Field_num(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                  field_name_arg, 0, zero_arg, unsigned_arg) {}
  Field_longlong(uint32 len_arg, bool is_nullable_arg,
                 const char *field_name_arg, bool unsigned_arg)
      : Field_num(nullptr, len_arg,
                  is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                  field_name_arg, 0, false, unsigned_arg) {}
  enum Item_result result_type() const final { return INT_RESULT; }
  enum_field_types type() const final { return MYSQL_TYPE_LONGLONG; }
  enum ha_base_keytype key_type() const final {
    return is_unsigned() ? HA_KEYTYPE_ULONGLONG : HA_KEYTYPE_LONGLONG;
  }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) override;
  double val_real() const final;
  longlong val_int() const override;
  String *val_str(String *, String *) const final;
  bool send_to_protocol(Protocol *protocol) const final;
  int cmp(const uchar *, const uchar *) const final;
  using Field_num::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  uint32 pack_length() const final { return PACK_LENGTH; }
  void sql_type(String &str) const final;
  bool can_be_compared_as_longlong() const final { return true; }
  uint32 max_display_length() const final { return 20; }
  Field_longlong *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_LONGLONG);
    return new (mem_root) Field_longlong(*this);
  }
  uchar *pack(uchar *to, const uchar *from, size_t max_length) const final {
    return pack_int64(to, from, max_length);
  }
  const uchar *unpack(uchar *to, const uchar *from,
                      uint param_data [[maybe_unused]]) final {
    return unpack_int64(to, from);
  }
 
  ulonglong get_max_int_value() const final {
    return is_unsigned() ? 0xFFFFFFFFFFFFFFFFULL : 0x7FFFFFFFFFFFFFFFULL;
  }
};
 
class Field_float final : public Field_real {
 public:
  Field_float(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
              uchar null_bit_arg, uchar auto_flags_arg,
              const char *field_name_arg, uint8 dec_arg, bool zero_arg,
              bool unsigned_arg)
      : Field_real(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                   field_name_arg, dec_arg, zero_arg, unsigned_arg) {}
  Field_float(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
              uint8 dec_arg, bool unsigned_arg)
      : Field_real(nullptr, len_arg,
                   is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                   field_name_arg, dec_arg, false, unsigned_arg) {}
  enum_field_types type() const final { return MYSQL_TYPE_FLOAT; }
  enum ha_base_keytype key_type() const final { return HA_KEYTYPE_FLOAT; }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  double val_real() const final;
  longlong val_int() const final;
  String *val_str(String *, String *) const final;
  bool send_to_protocol(Protocol *protocol) const final;
  int cmp(const uchar *, const uchar *) const final;
  using Field_real::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  uint32 pack_length() const final { return sizeof(float); }
  void sql_type(String &str) const final;
  Field_float *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_FLOAT);
    return new (mem_root) Field_float(*this);
  }
 
  ulonglong get_max_int_value() const final {
    /*
      We use the maximum as per IEEE754-2008 standard, 2^24
    */
    return 0x1000000ULL;
  }
 
 private:
  int do_save_field_metadata(uchar *first_byte) const final;
};
 
class Field_double final : public Field_real {
 public:
  Field_double(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
               uchar null_bit_arg, uchar auto_flags_arg,
               const char *field_name_arg, uint8 dec_arg, bool zero_arg,
               bool unsigned_arg)
      : Field_real(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                   field_name_arg, dec_arg, zero_arg, unsigned_arg) {}
  Field_double(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
               uint8 dec_arg)
      : Field_real(nullptr, len_arg,
                   is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                   field_name_arg, dec_arg, false, false) {}
  Field_double(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
               uint8 dec_arg, bool unsigned_arg)
      : Field_real(nullptr, len_arg,
                   is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                   field_name_arg, dec_arg, false, unsigned_arg) {}
  Field_double(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
               uint8 dec_arg, bool unsigned_arg, bool not_fixed_arg)
      : Field_real(nullptr, len_arg,
                   is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                   field_name_arg, dec_arg, false, unsigned_arg) {
    not_fixed = not_fixed_arg;
  }
  enum_field_types type() const final { return MYSQL_TYPE_DOUBLE; }
  enum ha_base_keytype key_type() const final { return HA_KEYTYPE_DOUBLE; }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  double val_real() const final;
  longlong val_int() const final;
  String *val_str(String *, String *) const final;
  bool send_to_protocol(Protocol *protocol) const final;
  int cmp(const uchar *, const uchar *) const final;
  using Field_real::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  uint32 pack_length() const final { return sizeof(double); }
  void sql_type(String &str) const final;
  Field_double *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_DOUBLE);
    return new (mem_root) Field_double(*this);
  }
 
  ulonglong get_max_int_value() const final {
    /*
      We use the maximum as per IEEE754-2008 standard, 2^53
    */
    return 0x20000000000000ULL;
  }
 
 private:
  int do_save_field_metadata(uchar *first_byte) const final;
};
 
/* Everything saved in this will disappear. It will always return NULL */
 
class Field_null final : public Field_str {
 public:
  Field_null(uchar *ptr_arg, uint32 len_arg, uchar auto_flags_arg,
             const char *field_name_arg, const CHARSET_INFO *cs)
      // (dummy_null_buffer & 32) is true, so is_null() always returns true.
      : Field_str(ptr_arg, len_arg, &dummy_null_buffer, 32, auto_flags_arg,
                  field_name_arg, cs) {}
  enum_field_types type() const final { return MYSQL_TYPE_NULL; }
  type_conversion_status store(const char *, size_t,
                               const CHARSET_INFO *) final {
    return TYPE_OK;
  }
  type_conversion_status store(double) final { return TYPE_OK; }
  type_conversion_status store(longlong, bool) final { return TYPE_OK; }
  type_conversion_status store_decimal(const my_decimal *) final {
    return TYPE_OK;
  }
  type_conversion_status reset() final { return TYPE_OK; }
  double val_real() const final { return 0.0; }
  longlong val_int() const final { return 0; }
  my_decimal *val_decimal(my_decimal *) const final { return nullptr; }
  String *val_str(String *, String *value2) const final {
    value2->length(0);
    return value2;
  }
  int cmp(const uchar *, const uchar *) const final { return 0; }
  using Field_str::make_sort_key;
  size_t make_sort_key(uchar *, size_t len) const final { return len; }
  uint32 pack_length() const final { return 0; }
  void sql_type(String &str) const final;
  uint32 max_display_length() const final { return 4; }
  Field_null *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_NULL);
    return new (mem_root) Field_null(*this);
  }
};
 
/*
  Abstract class for TIME, DATE, DATETIME, TIMESTAMP
*/
class Field_temporal : public Field {
 protected:
  uint8 dec;  // Number of fractional digits (N/A for DATE)
 
  /**
    Adjust number of decimal digits from DECIMAL_NOT_SPECIFIED to
    DATETIME_MAX_DECIMALS
  */
  static uint8 normalize_dec(uint8 dec_arg) {
    return dec_arg == DECIMAL_NOT_SPECIFIED ? DATETIME_MAX_DECIMALS : dec_arg;
  }
 
  /**
    Low level routine to store a MYSQL_TIME value into a field.
    The value must be already properly rounded or truncated
    and checked for being a valid TIME/DATE/DATETIME value.
 
    @param[in]  ltime   MYSQL_TIME value.
    @param[out] error   Error flag vector, set in case of error.
    @retval     false   In case of success.
    @retval     true    In case of error.
  */
  virtual type_conversion_status store_internal(const MYSQL_TIME *ltime,
                                                int *error) = 0;
 
  /**
    Low level routine to store a MYSQL_TIME value into a field
    with rounding/truncation according to the field decimals() value and
    sql_mode.
 
    @param[in]  ltime   MYSQL_TIME value.
    @param[out] warnings   Error flag vector, set in case of error.
    @retval     false   In case of success.
    @retval     true    In case of error.
  */
  virtual type_conversion_status store_internal_adjust_frac(MYSQL_TIME *ltime,
                                                            int *warnings) = 0;
 
  /**
    Store a temporal value in lldiv_t into a field,
    with rounding according to the field decimals() value.
 
    @param[in]  lld     Temporal value.
    @param[out] warning Warning flag vector.
    @retval     false   In case of success.
    @retval     true    In case of error.
  */
  type_conversion_status store_lldiv_t(const lldiv_t *lld, int *warning);
 
  /**
    Convert a string to MYSQL_TIME, according to the field type.
 
    @param[in]  str     String
    @param[in]  len     String length
    @param[in]  cs      String character set
    @param[out] ltime   The value is stored here
    @param[out] status  Conversion status
    @retval     false   Conversion went fine, ltime contains a valid time
    @retval     true    Conversion failed, ltime was reset and contains nothing
  */
  virtual bool convert_str_to_TIME(const char *str, size_t len,
                                   const CHARSET_INFO *cs, MYSQL_TIME *ltime,
                                   MYSQL_TIME_STATUS *status) = 0;
  /**
    Convert a number with fractional part with nanosecond precision
    into MYSQL_TIME, according to the field type. Nanoseconds
    are rounded to milliseconds and added to ltime->second_part.
 
    @param[in]  nr            Number
    @param[in]  unsigned_val  SIGNED/UNSIGNED flag
    @param[in]  nanoseconds   Fractional part in nanoseconds
    @param[out] ltime         The value is stored here
    @param[in,out] warning    Warnings found during execution
 
    @return Conversion status
    @retval     false         On success
    @retval     true          On error
  */
  virtual type_conversion_status convert_number_to_TIME(longlong nr,
                                                        bool unsigned_val,
                                                        int nanoseconds,
                                                        MYSQL_TIME *ltime,
                                                        int *warning) = 0;
 
  /**
    Convert an integer number into MYSQL_TIME, according to the field type.
 
    @param[in]  nr            Number
    @param[in]  unsigned_val  SIGNED/UNSIGNED flag
    @param[out] ltime         The value is stored here
    @param[in,out] warnings   Warnings found during execution
 
    @retval     false         On success
    @retval     true          On error
  */
  longlong convert_number_to_datetime(longlong nr, bool unsigned_val,
                                      MYSQL_TIME *ltime, int *warnings);
 
  /**
    Set warnings from a warning vector.
    Note, multiple warnings can be set at the same time.
    Every warning in the bit vector is set by an individual
    set_datetime_warning() call.
 
    @param str       Value.
    @param warnings  Warning vector.
 
    @retval false  Function reported warning
    @retval true   Function reported error
 
    @note STRICT mode can convert warnings to error.
   */
  [[nodiscard]] bool set_warnings(const ErrConvString &str, int warnings);
 
  /**
    Flags that are passed as "flag" argument to
    check_date(), number_to_datetime(), str_to_datetime().
 
    Flags depend on the session sql_mode settings, such as
    MODE_NO_ZERO_DATE, MODE_NO_ZERO_IN_DATE.
    Also, Field_date and Field_datetime add TIME_FUZZY_DATE
    to the session sql_mode settings, to allow relaxed date format,
    while Field_timestamp do not.
 
    @param  thd  THD
    @retval      sql_mode flags mixed with the field type flags.
  */
  virtual my_time_flags_t date_flags(const THD *thd [[maybe_unused]]) const {
    return 0;
  }
 
  /**
    Flags that are passed as "flag" argument to
    check_date(), number_to_datetime(), str_to_datetime().
    Similar to the above when we don't have a THD value.
  */
  my_time_flags_t date_flags() const;
 
  /**
    Produce warning or note about double datetime data saved into field.
 
    @param level            level of message (Note/Warning/Error)
    @param code             error code of message to be produced
    @param val              error parameter (the value)
    @param ts_type          type of datetime value (datetime/date/time)
    @param truncate_increment  whether we should increase truncated fields count
 
    @retval false  Function reported warning
    @retval true   Function reported error
 
    @note
      This function will always produce some warning but won't increase
    truncated fields counter if check_for_truncated_fields == FIELD_CHECK_IGNORE
      for current thread.
  */
  [[nodiscard]] bool set_datetime_warning(
      Sql_condition::enum_severity_level level, uint code,
      const ErrConvString &val, enum_mysql_timestamp_type ts_type,
      int truncate_increment);
 
 public:
  /**
    Constructor for Field_temporal
    @param ptr_arg           See Field definition
    @param null_ptr_arg      See Field definition
    @param null_bit_arg      See Field definition
    @param auto_flags_arg    See Field definition
    @param field_name_arg    See Field definition
    @param len_arg           Number of characters in the integer part.
    @param dec_arg           Number of second fraction digits, 0..6.
  */
  Field_temporal(uchar *ptr_arg, uchar *null_ptr_arg, uchar null_bit_arg,
                 uchar auto_flags_arg, const char *field_name_arg,
                 uint32 len_arg, uint8 dec_arg)
      : Field(ptr_arg,
              len_arg +
                  ((normalize_dec(dec_arg)) ? normalize_dec(dec_arg) + 1 : 0),
              null_ptr_arg, null_bit_arg, auto_flags_arg, field_name_arg) {
    set_flag(BINARY_FLAG);
    dec = normalize_dec(dec_arg);
  }
  Item_result result_type() const final { return STRING_RESULT; }
  uint32 max_display_length() const final { return field_length; }
  bool str_needs_quotes() const final { return true; }
  uint is_equal(const Create_field *new_field) const final;
  Item_result numeric_context_result_type() const final {
    return dec ? DECIMAL_RESULT : INT_RESULT;
  }
  enum Item_result cmp_type() const final { return INT_RESULT; }
  enum Derivation derivation() const final { return DERIVATION_NUMERIC; }
  uint repertoire() const final { return MY_REPERTOIRE_NUMERIC; }
  const CHARSET_INFO *charset() const final { return &my_charset_numeric; }
  bool can_be_compared_as_longlong() const final { return true; }
  bool binary() const final { return true; }
  type_conversion_status store(const char *str, size_t len,
                               const CHARSET_INFO *cs) final;
  type_conversion_status store_decimal(const my_decimal *decimal) final;
  type_conversion_status store(longlong nr, bool unsigned_val) override;
  type_conversion_status store(double nr) final;
  double val_real() const override  // FSP-enable types redefine it.
  {
    return (double)val_int();
  }
  [[nodiscard]] uint8 get_dec() const { return dec; }
  my_decimal *val_decimal(
      my_decimal *decimal_value) const override;  // FSP types redefine it
 
  my_time_flags_t get_date_flags(const THD *thd) const {
    return date_flags(thd);
  }
 
  uint8 get_fractional_digits() const { return dec; }
};
 
/**
  Abstract class for types with date
  with optional time, with or without fractional part:
  DATE, DATETIME, DATETIME(N), TIMESTAMP, TIMESTAMP(N).
*/
class Field_temporal_with_date : public Field_temporal {
 protected:
  /**
    Low level function to get value into MYSQL_TIME,
    without checking for being valid.
  */
  virtual bool get_date_internal(MYSQL_TIME *ltime) const = 0;
 
  virtual bool get_date_internal_at_utc(MYSQL_TIME *ltime) const {
    return get_date_internal(ltime);
  }
 
  /**
    Get value into MYSQL_TIME and check TIME_NO_ZERO_DATE flag.
    @retval   True on error: we get a zero value but flags disallow zero dates.
    @retval   False on success.
  */
  bool get_internal_check_zero(MYSQL_TIME *ltime,
                               my_time_flags_t fuzzydate) const;
 
  type_conversion_status convert_number_to_TIME(longlong nr, bool unsigned_val,
                                                int nanoseconds,
                                                MYSQL_TIME *ltime,
                                                int *warning) final;
  bool convert_str_to_TIME(const char *str, size_t len, const CHARSET_INFO *cs,
                           MYSQL_TIME *ltime, MYSQL_TIME_STATUS *status) final;
 
  type_conversion_status store_internal_adjust_frac(MYSQL_TIME *ltime,
                                                    int *warnings) final;
  using Field_temporal::date_flags;
 
 public:
  /**
    Constructor for Field_temporal
    @param ptr_arg           See Field definition
    @param null_ptr_arg      See Field definition
    @param null_bit_arg      See Field definition
    @param auto_flags_arg    See Field definition
    @param field_name_arg    See Field definition
    @param int_length_arg    Number of characters in the integer part.
    @param dec_arg           Number of second fraction digits, 0..6.
  */
  Field_temporal_with_date(uchar *ptr_arg, uchar *null_ptr_arg,
                           uchar null_bit_arg, uchar auto_flags_arg,
                           const char *field_name_arg, uint8 int_length_arg,
                           uint8 dec_arg)
      : Field_temporal(ptr_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                       field_name_arg, int_length_arg, dec_arg) {}
  bool send_to_protocol(Protocol *protocol) const override;
  type_conversion_status store_time(Time_val time, uint8 dec_arg) override;
  type_conversion_status store_time(MYSQL_TIME *ltime, uint8 dec) final;
  String *val_str(String *, String *) const override;
  longlong val_date_temporal() const override;
  longlong val_date_temporal_at_utc() const override;
  bool val_time(Time_val *time) const final;
  /* Validate the value stored in a field */
  type_conversion_status validate_stored_val(THD *thd) override;
};
 
/**
  Abstract class for types with date and time:
  DATETIME, DATETIME(N), TIMESTAMP, TIMESTAMP(N).
*/
class Field_temporal_with_date_and_time : public Field_temporal_with_date {
 private:
  int do_save_field_metadata(uchar *metadata_ptr) const final {
    *metadata_ptr = decimals();
    return 1;
  }
 
 public:
  /**
    Constructor for Field_temporal_with_date_and_time
    @param ptr_arg           See Field definition
    @param null_ptr_arg      See Field definition
    @param null_bit_arg      See Field definition
    @param auto_flags_arg    See Field definition
    @param field_name_arg    See Field definition
    @param dec_arg           Number of second fraction digits, 0..6.
  */
  Field_temporal_with_date_and_time(uchar *ptr_arg, uchar *null_ptr_arg,
                                    uchar null_bit_arg, uchar auto_flags_arg,
                                    const char *field_name_arg, uint8 dec_arg)
      : Field_temporal_with_date(ptr_arg, null_ptr_arg, null_bit_arg,
                                 auto_flags_arg, field_name_arg,
                                 MAX_DATETIME_WIDTH, dec_arg) {}
 
  uint decimals() const final { return dec; }
  const CHARSET_INFO *sort_charset() const final { return &my_charset_bin; }
  using Field_temporal_with_date::make_sort_key;
  size_t make_sort_key(uchar *to, size_t length) const final {
    memcpy(to, ptr, length);
    return length;
  }
  int cmp(const uchar *a_ptr, const uchar *b_ptr) const final {
    return memcmp(a_ptr, b_ptr, pack_length());
  }
  uint row_pack_length() const final { return pack_length(); }
  double val_real() const final;
  longlong val_int() const final;
  my_decimal *val_decimal(my_decimal *decimal_value) const final;
 
  void store_timestamp(const my_timeval *tm) override;
 
 protected:
  /**
     Initialize flags for TIMESTAMP DEFAULT CURRENT_TIMESTAMP / ON UPDATE
     CURRENT_TIMESTAMP columns.
 
     @todo get rid of TIMESTAMP_FLAG and ON_UPDATE_NOW_FLAG.
  */
  void init_timestamp_flags();
  /**
    Store "struct timeval" value into field.
    The value must be properly rounded or truncated according
    to the number of fractional second digits.
  */
  virtual void store_timestamp_internal(const my_timeval *tm) = 0;
  bool convert_TIME_to_timestamp(const MYSQL_TIME *ltime, const Time_zone &tz,
                                 my_timeval *tm, int *error);
};
 
/*
  Field implementing TIMESTAMP(N) data type, where N=0..6.
*/
class Field_timestamp : public Field_temporal_with_date_and_time {
 protected:
  bool get_date_internal(MYSQL_TIME *ltime) const final;
  bool get_date_internal_at_utc(MYSQL_TIME *ltime) const final;
  type_conversion_status store_internal(const MYSQL_TIME *ltime,
                                        int *error) final;
  my_time_flags_t date_flags(const THD *thd) const final;
  void store_timestamp_internal(const my_timeval *tm) override;
 
 public:
  /**
    Field_timestamp constructor
    @param ptr_arg           See Field definition
    @param null_ptr_arg      See Field definition
    @param null_bit_arg      See Field definition
    @param auto_flags_arg    See Field definition
    @param field_name_arg    See Field definition
    @param dec_arg           Number of fractional second digits, 0..6.
  */
  Field_timestamp(uchar *ptr_arg, uchar *null_ptr_arg, uchar null_bit_arg,
                  uchar auto_flags_arg, const char *field_name_arg,
                  uint8 dec_arg);
  /**
    Field_timestamp constructor
    @param is_nullable_arg   See Field definition
    @param field_name_arg    See Field definition
    @param dec_arg           Number of fractional second digits, 0..6.
  */
  Field_timestamp(bool is_nullable_arg, const char *field_name_arg,
                  uint8 dec_arg);
  Field_timestamp *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_TIMESTAMP);
    return new (mem_root) Field_timestamp(*this);
  }
 
  enum_field_types type() const final { return MYSQL_TYPE_TIMESTAMP; }
  enum_field_types real_type() const final { return MYSQL_TYPE_TIMESTAMP2; }
  enum_field_types binlog_type() const final { return MYSQL_TYPE_TIMESTAMP2; }
  bool zero_pack() const final { return false; }
 
  uint32 pack_length() const final { return my_timestamp_binary_length(dec); }
  uint pack_length_from_metadata(uint field_metadata) const final {
    DBUG_TRACE;
    const uint tmp = my_timestamp_binary_length(field_metadata);
    return tmp;
  }
 
  type_conversion_status store_packed(longlong nr) final;
  bool val_date(Date_val *date, my_time_flags_t flags) const final;
  bool val_datetime(Datetime_val *dt, my_time_flags_t flags) const final;
  void sql_type(String &str) const final;
 
  bool get_timestamp(my_timeval *tm, int *warnings) const final;
  /* Validate the value stored in a field */
  type_conversion_status validate_stored_val(THD *thd) final;
 
 private:
  /**
    Retrieves a value from a record, without checking fuzzy date flags.
 
    @param tz The time zone to convert to
    @param[out] ltime The timestamp value in the time zone.
 
    @retval true  Means that the timestamp value read is 0. ltime is not touched
    in this case.
    @retval false If timestamp is non-zero.
  */
  bool get_date_internal_at(const Time_zone *tz, MYSQL_TIME *ltime) const;
};
 
class Field_year final : public Field_tiny {
 public:
  enum Limits { MIN_YEAR = 1901, MAX_YEAR = 2155 };
  Field_year(uchar *ptr_arg, uchar *null_ptr_arg, uchar null_bit_arg,
             uchar auto_flags_arg, const char *field_name_arg)
      : Field_tiny(ptr_arg, 4, null_ptr_arg, null_bit_arg, auto_flags_arg,
                   field_name_arg, true, true) {}
  Field_year(bool is_nullable_arg, const char *field_name_arg)
      : Field_tiny(nullptr, 4, is_nullable_arg ? &dummy_null_buffer : nullptr,
                   0, NONE, field_name_arg, true, true) {}
  enum_field_types type() const final { return MYSQL_TYPE_YEAR; }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  type_conversion_status store_time(Time_val time, uint8 dec_arg) final;
  type_conversion_status store_time(MYSQL_TIME *ltime, uint8 dec) final;
  double val_real() const final;
  longlong val_int() const final;
  String *val_str(String *, String *) const final;
  bool send_to_protocol(Protocol *protocol) const final;
  void sql_type(String &str) const final;
  bool can_be_compared_as_longlong() const final { return true; }
  Field_year *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_YEAR);
    return new (mem_root) Field_year(*this);
  }
};
 
class Field_date : public Field_temporal_with_date {
 protected:
  static const int PACK_LENGTH = 3;
  my_time_flags_t date_flags(const THD *thd) const final;
  bool get_date_internal(MYSQL_TIME *ltime) const final;
  type_conversion_status store_internal(const MYSQL_TIME *ltime,
                                        int *error) final;
 
 public:
  Field_date(uchar *ptr_arg, uchar *null_ptr_arg, uchar null_bit_arg,
             uchar auto_flags_arg, const char *field_name_arg)
      : Field_temporal_with_date(ptr_arg, null_ptr_arg, null_bit_arg,
                                 auto_flags_arg, field_name_arg, MAX_DATE_WIDTH,
                                 0) {}
  Field_date(bool is_nullable_arg, const char *field_name_arg)
      : Field_temporal_with_date(nullptr,
                                 is_nullable_arg ? &dummy_null_buffer : nullptr,
                                 0, NONE, field_name_arg, MAX_DATE_WIDTH, 0) {}
  enum_field_types type() const final { return MYSQL_TYPE_DATE; }
  enum_field_types real_type() const final { return MYSQL_TYPE_NEWDATE; }
  enum ha_base_keytype key_type() const final { return HA_KEYTYPE_UINT24; }
  type_conversion_status store_packed(longlong nr) final;
  longlong val_int() const final;
  longlong val_date_temporal() const final;
  String *val_str(String *, String *) const final;
  bool send_to_protocol(Protocol *protocol) const final;
  int cmp(const uchar *, const uchar *) const final;
  using Field_temporal_with_date::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  uint32 pack_length() const final { return PACK_LENGTH; }
  void sql_type(String &str) const final;
  bool zero_pack() const final { return true; }
  bool val_date(Date_val *date, my_time_flags_t flags) const final;
  bool val_datetime(Datetime_val *dt, my_time_flags_t flags) const final;
  Field_date *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_DATE);
    assert(real_type() == MYSQL_TYPE_NEWDATE);
    return new (mem_root) Field_date(*this);
  }
};
 
/**
  Field implementing TIME(N) data type, where N=0..6.
*/
class Field_time final : public Field_temporal {
 private:
  int do_save_field_metadata(uchar *metadata_ptr) const final {
    *metadata_ptr = decimals();
    return 1;
  }
 
 protected:
  type_conversion_status store_internal(const MYSQL_TIME *ltime,
                                        int *error) final;
 
  bool convert_str_to_TIME(const char *str, size_t len, const CHARSET_INFO *cs,
                           MYSQL_TIME *ltime, MYSQL_TIME_STATUS *status) final;
  /**
    @todo: convert_number_to_TIME returns conversion status through
    two different interfaces: return value and warning. It should be
    refactored to only use return value.
   */
  type_conversion_status convert_number_to_TIME(longlong nr, bool unsigned_val,
                                                int nanoseconds,
                                                MYSQL_TIME *ltime,
                                                int *warning) final;
  /**
    Function to store time value.
    The value is rounded/truncated according to decimals() and sql_mode.
  */
  type_conversion_status store_internal_adjust_frac(MYSQL_TIME *ltime,
                                                    int *warnings) final;
 
  my_time_flags_t date_flags(const THD *thd) const final;
  using Field_temporal::date_flags;
 
 public:
  /**
    Constructor for Field_time
    @param ptr_arg           See Field definition
    @param null_ptr_arg      See Field definition
    @param null_bit_arg      See Field definition
    @param auto_flags_arg    See Field definition
    @param field_name_arg    See Field definition
    @param dec_arg           Number of second fraction digits, 0..6.
  */
  Field_time(uchar *ptr_arg, uchar *null_ptr_arg, uchar null_bit_arg,
             uchar auto_flags_arg, const char *field_name_arg, uint8 dec_arg)
      : Field_temporal(ptr_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                       field_name_arg, MAX_TIME_WIDTH, dec_arg) {}
  /**
    Constructor for Field_time
    @param is_nullable_arg   See Field definition
    @param field_name_arg    See Field definition
    @param dec_arg           Number of second fraction digits, 0..6.
  */
  Field_time(bool is_nullable_arg, const char *field_name_arg, uint8 dec_arg)
      : Field_temporal(nullptr, is_nullable_arg ? &dummy_null_buffer : nullptr,
                       0, NONE, field_name_arg, MAX_TIME_WIDTH, dec_arg) {}
  Field_time *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_TIME);
    return new (mem_root) Field_time(*this);
  }
  uint decimals() const final { return dec; }
  enum_field_types type() const final { return MYSQL_TYPE_TIME; }
  enum_field_types real_type() const final { return MYSQL_TYPE_TIME2; }
  enum_field_types binlog_type() const final { return MYSQL_TYPE_TIME2; }
  type_conversion_status store_time(Time_val time, uint8 dec_arg) final;
  type_conversion_status store_time(MYSQL_TIME *ltime, uint8 dec) final;
  type_conversion_status reset() final;
  double val_real() const final;
  longlong val_int() const final;
  String *val_str(String *, String *) const final;
  bool val_date(Date_val *date, my_time_flags_t flags) const final;
  bool val_datetime(Datetime_val *dt, my_time_flags_t flags) const final;
  longlong val_date_temporal() const final;
  bool send_to_protocol(Protocol *protocol) const final;
  bool val_time(Time_val *time) const final;
  my_decimal *val_decimal(my_decimal *) const final;
  uint32 pack_length() const final { return my_time_binary_length(dec); }
  uint pack_length_from_metadata(uint field_metadata) const final {
    DBUG_TRACE;
    const uint tmp = my_time_binary_length(field_metadata);
    return tmp;
  }
  uint row_pack_length() const final { return pack_length(); }
  void sql_type(String &str) const final;
  bool zero_pack() const final { return true; }
  const CHARSET_INFO *sort_charset() const final { return &my_charset_bin; }
  using Field_temporal::make_sort_key;
  size_t make_sort_key(uchar *to, size_t length) const final {
    memcpy(to, ptr, length);
    return length;
  }
  int cmp(const uchar *a_ptr, const uchar *b_ptr) const final {
    return memcmp(a_ptr, b_ptr, pack_length());
  }
};
 
/*
  Field implementing DATETIME(N) data type, where N=0..6.
*/
class Field_datetime : public Field_temporal_with_date_and_time {
 protected:
  bool get_date_internal(MYSQL_TIME *ltime) const final;
  type_conversion_status store_internal(const MYSQL_TIME *ltime,
                                        int *error) final;
  my_time_flags_t date_flags(const THD *thd) const final;
  void store_timestamp_internal(const my_timeval *tm) final;
 
 public:
  /**
    Constructor for Field_datetime
    @param ptr_arg           See Field definition
    @param null_ptr_arg      See Field definition
    @param null_bit_arg      See Field definition
    @param auto_flags_arg    See Field definition
    @param field_name_arg    See Field definition
    @param dec_arg           Number of second fraction digits, 0..6.
  */
  Field_datetime(uchar *ptr_arg, uchar *null_ptr_arg, uchar null_bit_arg,
                 uchar auto_flags_arg, const char *field_name_arg,
                 uint8 dec_arg)
      : Field_temporal_with_date_and_time(ptr_arg, null_ptr_arg, null_bit_arg,
                                          auto_flags_arg, field_name_arg,
                                          dec_arg) {}
  /**
    Constructor for Field_datetime
    @param is_nullable_arg   See Field definition
    @param field_name_arg    See Field definition
    @param dec_arg           Number of second fraction digits, 0..6.
  */
  Field_datetime(bool is_nullable_arg, const char *field_name_arg,
                 uint8 dec_arg)
      : Field_temporal_with_date_and_time(
            nullptr, is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
            field_name_arg, dec_arg) {}
  Field_datetime(const char *field_name_arg)
      : Field_temporal_with_date_and_time(nullptr, nullptr, 0, NONE,
                                          field_name_arg, 0) {}
  Field_datetime *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_DATETIME);
    return new (mem_root) Field_datetime(*this);
  }
 
  enum_field_types type() const final { return MYSQL_TYPE_DATETIME; }
  enum_field_types real_type() const final { return MYSQL_TYPE_DATETIME2; }
  enum_field_types binlog_type() const final { return MYSQL_TYPE_DATETIME2; }
  uint32 pack_length() const final { return my_datetime_binary_length(dec); }
  uint pack_length_from_metadata(uint field_metadata) const final {
    DBUG_TRACE;
    const uint tmp = my_datetime_binary_length(field_metadata);
    return tmp;
  }
  bool zero_pack() const final { return true; }
 
  type_conversion_status store_packed(longlong nr) final;
  type_conversion_status reset() final;
  longlong val_date_temporal() const final;
  bool val_date(Date_val *date, my_time_flags_t flags) const final;
  bool val_datetime(Datetime_val *dt, my_time_flags_t flags) const final;
  void sql_type(String &str) const final;
};
 
class Field_string : public Field_longstr {
 public:
  Field_string(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
               uchar null_bit_arg, uchar auto_flags_arg,
               const char *field_name_arg, const CHARSET_INFO *cs)
      : Field_longstr(ptr_arg, len_arg, null_ptr_arg, null_bit_arg,
                      auto_flags_arg, field_name_arg, cs) {}
  Field_string(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
               const CHARSET_INFO *cs)
      : Field_longstr(nullptr, len_arg,
                      is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                      field_name_arg, cs) {}
 
  enum_field_types type() const final { return MYSQL_TYPE_STRING; }
  bool match_collation_to_optimize_range() const final { return true; }
  enum ha_base_keytype key_type() const final {
    return binary() ? HA_KEYTYPE_BINARY : HA_KEYTYPE_TEXT;
  }
  bool zero_pack() const final { return false; }
  type_conversion_status reset() final {
    charset()->cset->fill(charset(), (char *)ptr, field_length,
                          (has_charset() ? ' ' : 0));
    return TYPE_OK;
  }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  // Inherit the store() overloads that have not been overridden.
  using Field_longstr::store;
  double val_real() const final;
  longlong val_int() const final;
  String *val_str(String *, String *) const final;
  /**
     Get the C-string value, without using String class.
     @returns The C-string value of this field.
  */
  LEX_CSTRING val_str_quick() const {
    const char *string = pointer_cast<const char *>(ptr);
    return {string,
            field_charset->cset->lengthsp(field_charset, string, field_length)};
  }
  my_decimal *val_decimal(my_decimal *) const final;
  int cmp(const uchar *, const uchar *) const final;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  size_t make_sort_key(uchar *to, size_t length, size_t trunc_pos) const final;
  void sql_type(String &str) const final;
  uchar *pack(uchar *to, const uchar *from, size_t max_length) const final;
  const uchar *unpack(uchar *to, const uchar *from, uint param_data) final;
  uint pack_length_from_metadata(uint field_metadata) const final {
    DBUG_PRINT("debug", ("field_metadata: 0x%04x", field_metadata));
    if (field_metadata == 0) return row_pack_length();
    return (((field_metadata >> 4) & 0x300) ^ 0x300) +
           (field_metadata & 0x00ff);
  }
  bool compatible_field_size(uint field_metadata, Relay_log_info *rli,
                             uint16 mflags, int *order_var) const final;
  uint row_pack_length() const final { return field_length; }
  uint max_packed_col_length() const final;
  enum_field_types real_type() const final { return MYSQL_TYPE_STRING; }
  bool has_charset() const final {
    return charset() == &my_charset_bin ? false : true;
  }
  Field_string *clone(MEM_ROOT *mem_root) const final {
    assert(real_type() == MYSQL_TYPE_STRING);
    return new (mem_root) Field_string(*this);
  }
  size_t get_key_image(uchar *buff, size_t length, imagetype type) const final;
  bool is_text_key_type() const final { return binary() ? false : true; }
 
 private:
  int do_save_field_metadata(uchar *first_byte) const final;
};
 
class Field_varstring : public Field_longstr {
 public:
  Field_varstring(uchar *ptr_arg, uint32 len_arg, uint length_bytes_arg,
                  uchar *null_ptr_arg, uchar null_bit_arg, uchar auto_flags_arg,
                  const char *field_name_arg, TABLE_SHARE *share,
                  const CHARSET_INFO *cs);
  Field_varstring(uint32 len_arg, bool is_nullable_arg,
                  const char *field_name_arg, TABLE_SHARE *share,
                  const CHARSET_INFO *cs);
 
  enum_field_types type() const final { return MYSQL_TYPE_VARCHAR; }
  bool match_collation_to_optimize_range() const final { return true; }
  enum ha_base_keytype key_type() const final;
  uint row_pack_length() const final { return field_length; }
  bool zero_pack() const final { return false; }
  uint32 pack_length() const final {
    return (uint32)field_length + length_bytes;
  }
  uint32 key_length() const final { return (uint32)field_length; }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) override;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  // Inherit the store() overloads that have not been overridden.
  using Field_longstr::store;
  double val_real() const final;
  longlong val_int() const final;
  String *val_str(String *, String *) const override;
  my_decimal *val_decimal(my_decimal *) const final;
  int cmp_max(const uchar *, const uchar *, uint max_length) const final;
  int cmp(const uchar *a, const uchar *b) const final {
    return cmp_max(a, b, ~0U);
  }
  size_t make_sort_key(uchar *buff, size_t length) const final;
  size_t make_sort_key(uchar *to, size_t length, size_t trunc_pos) const final;
  size_t get_key_image(uchar *buff, size_t length, imagetype type) const final;
  void set_key_image(const uchar *buff, size_t length) final;
  void sql_type(String &str) const final;
  uchar *pack(uchar *to, const uchar *from, size_t max_length) const final;
  const uchar *unpack(uchar *to, const uchar *from, uint param_data) final;
  int cmp_binary(const uchar *a, const uchar *b,
                 uint32 max_length = ~0L) const final;
  int key_cmp(const uchar *, const uchar *) const final;
  int key_cmp(const uchar *str, uint length) const final;
 
  uint32 data_length(ptrdiff_t row_offset = 0) const final;
  enum_field_types real_type() const final { return MYSQL_TYPE_VARCHAR; }
  bool has_charset() const final {
    return charset() == &my_charset_bin ? false : true;
  }
  Field *new_field(MEM_ROOT *root, TABLE *new_table) const final;
  Field *new_key_field(MEM_ROOT *root, TABLE *new_table, uchar *new_ptr,
                       uchar *new_null_ptr, uint new_null_bit) const final;
  Field_varstring *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_VARCHAR);
    assert(real_type() == MYSQL_TYPE_VARCHAR);
    return new (mem_root) Field_varstring(*this);
  }
  uint is_equal(const Create_field *new_field) const final;
  void hash(ulong *nr, ulong *nr2) const final;
  const uchar *data_ptr() const final { return ptr + length_bytes; }
  bool is_text_key_type() const final { return binary() ? false : true; }
  uint32 get_length_bytes() const override { return length_bytes; }
 
 private:
  /* Store number of bytes used to store length (1 or 2) */
  uint32 length_bytes;
 
  int do_save_field_metadata(uchar *first_byte) const final;
};
 
class Field_blob : public Field_longstr {
  virtual type_conversion_status store_internal(const char *from, size_t length,
                                                const CHARSET_INFO *cs);
  /**
    Copy value to memory storage.
  */
  type_conversion_status store_to_mem(const char *from, size_t length,
                                      const CHARSET_INFO *cs, size_t max_length,
                                      Blob_mem_storage *);
 
 protected:
  /**
    The number of bytes used to represent the length of the blob.
  */
  uint packlength;
 
  /**
    The 'value'-object is a cache fronting the storage engine.
  */
  String value;
 
 private:
  /**
    In order to support update of virtual generated columns of blob type,
    we need to allocate the space blob needs on server for old_row and
    new_row respectively. This variable is used to record the
    allocated blob space for old_row.
  */
  String old_value;
 
  /**
    Whether we need to move the content of 'value' to 'old_value' before
    updating the BLOB stored in 'value'. This needs to be done for
    updates of BLOB columns that are virtual since the storage engine
    does not have its own copy of the old 'value'. This variable is set
    to true when we read the data into 'value'. It is reset when we move
    'value' to 'old_value'. The purpose of having this is to avoid that we
    do the move operation from 'value' to 'old_value' more than one time per
    record.
    Currently, this variable is introduced because the following call in
    sql_data_change.cc:
    \/\**
      @todo combine this call to update_generated_write_fields() with the one
      in fill_record() to avoid updating virtual generated fields twice.
    *\/
     if (table->has_gcol())
            update_generated_write_fields(table->write_set, table);
     When the @todo is done, m_keep_old_value can be deleted.
  */
  bool m_keep_old_value;
 
  /**
    Backup String for table's blob fields.
    UPDATE of a virtual field (for index update) requires two values to be
    kept at the same time - 'new' and 'old' since SE (InnoDB) doesn't know the
    latter. In the case when there was an indexed record, it got deleted and
    When INSERT inserts into an index a record that coincides with a
    previously deleted one, InnoDB needs to recalculate value that was
    deleted in order to properly insert the new one.
    When two above overlap, a field have to keep 3 different values at the
    same time - 'new', 'old' and 'deleted'.
    This backup_value is used by @see my_eval_gcolumn_expr_helper() to save
    'new' and provide space for 'deleted' to avoid thrashing the former.
    Unlike the old_value, backup_value is allocated once and reused for each
    new re-calculation, to avoid excessive [re-]allocations. It's freed at the
    end of statement. Since InnoDB consumes calculated values only after all
    needed table's virtual fields were calculated, we have to have such backup
    buffer for each field.
 
    Also used for set operation hashing: we need to compare the new
    and the existing record with the same hash.
  */
  String m_blob_backup;
 
#ifndef NDEBUG
  /**
    Whether the field uses table's backup value storage. @see
    TABLE::m_blob_backup. Used only for debug.
  */
  bool m_uses_backup{false};
#endif
 
 protected:
  /**
    Store ptr and length.
  */
  void store_ptr_and_length(const char *from, uint32 length) {
    store_length(length);
    memmove(ptr + packlength, &from, sizeof(char *));
  }
 
 public:
  Field_blob(uchar *ptr_arg, uchar *null_ptr_arg, uchar null_bit_arg,
             uchar auto_flags_arg, const char *field_name_arg,
             TABLE_SHARE *share, uint blob_pack_length, const CHARSET_INFO *cs);
 
  Field_blob(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
             const CHARSET_INFO *cs, bool set_packlength)
      : Field_longstr(nullptr, len_arg,
                      is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                      field_name_arg, cs),
        packlength(4),
        m_keep_old_value(false) {
    set_flag(BLOB_FLAG);
    if (set_packlength) {
      packlength = len_arg <= 255        ? 1
                   : len_arg <= 65535    ? 2
                   : len_arg <= 16777215 ? 3
                                         : 4;
    }
  }
 
  /// Copy static information and reset dynamic information.
  Field_blob(const Field_blob &field)
      : Field_longstr(field),
        packlength(field.packlength),
        value(),
        old_value(),
        m_keep_old_value(field.m_keep_old_value),
        m_blob_backup() {
#ifndef NDEBUG
    m_uses_backup = field.m_uses_backup;
#endif
  }
 
  explicit Field_blob(uint32 packlength_arg);
 
  /* Note that the default copy constructor is used, in clone() */
  enum_field_types type() const override { return MYSQL_TYPE_BLOB; }
  bool match_collation_to_optimize_range() const override { return true; }
  enum ha_base_keytype key_type() const override {
    return binary() ? HA_KEYTYPE_VARBINARY2 : HA_KEYTYPE_VARTEXT2;
  }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) override;
  type_conversion_status store(double nr) override;
  type_conversion_status store(longlong nr, bool unsigned_val) override;
  type_conversion_status store(const Field *from);
  double val_real() const override;
  longlong val_int() const override;
  String *val_str(String *, String *) const override;
  my_decimal *val_decimal(my_decimal *) const override;
  int cmp_max(const uchar *, const uchar *, uint max_length) const final;
  int cmp(const uchar *a, const uchar *b) const final {
    return cmp_max(a, b, ~0U);
  }
  int cmp(const uchar *a, uint32 a_length, const uchar *b,
          uint32 b_length) const;  // No override.
  int cmp_binary(const uchar *a, const uchar *b,
                 uint32 max_length = ~0L) const override;
  int key_cmp(const uchar *, const uchar *) const override;
  int key_cmp(const uchar *str, uint length) const override;
  uint32 key_length() const override { return 0; }
  size_t make_sort_key(uchar *buff, size_t length) const override;
  size_t make_sort_key(uchar *to, size_t length, size_t trunc_pos) const final;
  uint32 pack_length() const final {
    return (uint32)(packlength + portable_sizeof_char_ptr);
  }
 
  /**
     Return the packed length without the pointer size added.
 
     This is used to determine the size of the actual data in the row
     buffer.
 
     @returns The length of the raw data itself without the pointer.
  */
  uint32 pack_length_no_ptr() const { return (uint32)(packlength); }
  uint row_pack_length() const final { return pack_length_no_ptr(); }
  uint32 max_data_length() const override {
    return (uint32)(((ulonglong)1 << (packlength * 8)) - 1);
  }
  size_t get_field_buffer_size() { return value.alloced_length(); }
  void store_length(uchar *i_ptr, uint i_packlength, uint32 i_number);
  inline void store_length(uint32 number) {
    store_length(ptr, packlength, number);
  }
  uint32 data_length(ptrdiff_t row_offset = 0) const final {
    return get_length(row_offset);
  }
  uint32 get_length(ptrdiff_t row_offset = 0) const;
  uint32 get_length(const uchar *ptr, uint packlength) const;
  uint32 get_length(const uchar *ptr_arg) const;
  /** Get a const pointer to the BLOB data of this field. */
  const uchar *get_blob_data() const { return get_blob_data(ptr + packlength); }
  /** Get a non-const pointer to the BLOB data of this field. */
  uchar *get_blob_data(ptrdiff_t row_offset = 0) {
    // row_offset is only used by NDB
    return get_blob_data(ptr + packlength + row_offset);
  }
  /** Get a const pointer to the BLOB data of this field. */
  const uchar *data_ptr() const final { return get_blob_data(); }
 
 protected:
  /**
    Get the BLOB data pointer stored at the specified position in the record
    buffer.
  */
  static uchar *get_blob_data(const uchar *position) {
    uchar *data;
    memcpy(&data, position, sizeof(data));
    return data;
  }
 
 public:
  void set_ptr(const uchar *length, const uchar *data) {
    memcpy(ptr, length, packlength);
    memcpy(ptr + packlength, &data, sizeof(char *));
  }
  void set_ptr_offset(ptrdiff_t ptr_diff, uint32 length, const uchar *data) {
    uchar *ptr_ofs = ptr + ptr_diff;
    store_length(ptr_ofs, packlength, length);
    memcpy(ptr_ofs + packlength, &data, sizeof(char *));
  }
  void set_ptr(uint32 length, const uchar *data) {
    set_ptr_offset(0, length, data);
  }
  size_t get_key_image(uchar *buff, size_t length,
                       imagetype type) const override;
  void set_key_image(const uchar *buff, size_t length) final;
  void sql_type(String &str) const override;
  bool copy();
  Field_blob *clone(MEM_ROOT *mem_root) const override {
    assert(type() == MYSQL_TYPE_BLOB);
    return new (mem_root) Field_blob(*this);
  }
  uchar *pack(uchar *to, const uchar *from, size_t max_length) const final;
  uchar *pack_with_metadata_bytes(uchar *to, const uchar *from,
                                  uint max_length) const final;
  const uchar *unpack(uchar *, const uchar *from, uint param_data) final;
  uint max_packed_col_length() const final;
  void mem_free() final {
    // Free all allocated space
    value.mem_free();
    old_value.mem_free();
    m_blob_backup.mem_free();
  }
  bool has_charset() const override {
    return charset() == &my_charset_bin ? false : true;
  }
  uint32 max_display_length() const final;
  uint32 char_length() const override;
  bool copy_blob_value(MEM_ROOT *mem_root);
  uint is_equal(const Create_field *new_field) const override;
  bool is_text_key_type() const final { return binary() ? false : true; }
 
  /**
    Mark that the BLOB stored in value should be copied before updating it.
 
    When updating virtual generated columns we need to keep the old
    'value' for BLOBs since this can be needed when the storage engine
    does the update. During read of the record the old 'value' for the
    BLOB is evaluated and stored in 'value'. This function is to be used
    to specify that we need to copy this BLOB 'value' into 'old_value'
    before we compute the new BLOB 'value'. For more information @see
    Field_blob::keep_old_value().
  */
  void set_keep_old_value(bool old_value_flag) {
    /*
      We should only need to keep a copy of the blob 'value' in the case
      where this is a virtual generated column (that is indexed).
    */
    assert(is_virtual_gcol());
 
    /*
      If set to true, ensure that 'value' is copied to 'old_value' when
      keep_old_value() is called.
    */
    m_keep_old_value = old_value_flag;
  }
 
  /**
    Save the current BLOB value to avoid that it gets overwritten.
 
    This is used when updating virtual generated columns that are
    BLOBs. Some storage engines require that we have both the old and
    new BLOB value for virtual generated columns that are indexed in
    order for the storage engine to be able to maintain the index. This
    function will transfer the buffer storing the current BLOB value
    from 'value' to 'old_value'. This avoids that the current BLOB value
    is over-written when the new BLOB value is saved into this field.
 
    The reason this requires special handling when updating/deleting
    virtual columns of BLOB type is that the BLOB value is not known to
    the storage engine. For stored columns, the "old" BLOB value is read
    by the storage engine, Field_blob is made to point to the engine's
    internal buffer; Field_blob's internal buffer (Field_blob::value)
    isn't used and remains available to store the "new" value.  For
    virtual generated columns, the "old" value is written directly into
    Field_blob::value when reading the record to be
    updated/deleted. This is done in update_generated_read_fields().
    Since, in this case, the "old" value already occupies the place to
    store the "new" value, we must call this function before we write
    the "new" value into Field_blob::value object so that the "old"
    value does not get over-written. The table->record[1] buffer will
    have a pointer that points to the memory buffer inside
    old_value. The storage engine will use table->record[1] to read the
    old value for the BLOB and use table->record[0] to read the new
    value.
 
    This function must be called before we store the new BLOB value in
    this field object.
  */
  void keep_old_value() {
    /*
      We should only need to keep a copy of the blob value in the case
      where this is a virtual generated column (that is indexed).
    */
    assert(is_virtual_gcol());
 
    // Transfer ownership of the current BLOB value to old_value
    if (m_keep_old_value) {
      old_value.takeover(value);
      m_keep_old_value = false;
    }
  }
 
  /**
    Use to store the blob value into an allocated space.
  */
  void store_in_allocated_space(const char *from, uint32 length) {
    store_ptr_and_length(from, length);
  }
 
  /**
    Backup data stored in 'value' into the backup_value
    @see Field_blob::backup_value
 
    @returns
      true  if backup fails
      false otherwise
  */
  bool backup_blob_field();
 
  /**
    Restore backup value
    @see Field_blob::backup_value
  */
  void restore_blob_backup();
 
 private:
  int do_save_field_metadata(uchar *first_byte) const override;
};
 
class Field_vector : public Field_blob {
 public:
  static const uint32 max_dimensions = vector_constants::max_dimensions;
  static const uint32 precision = sizeof(float);
  static uint32 dimension_bytes(uint32 dimensions) {
    return precision * dimensions;
  }
  uint32 get_max_dimensions() const {
    return get_dimensions(field_length, precision);
  }
 
  Field_vector(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
               uchar null_bit_arg, uchar auto_flags_arg,
               const char *field_name_arg, TABLE_SHARE *share,
               uint blob_pack_length, const CHARSET_INFO *cs)
      : Field_blob(ptr_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                   field_name_arg, share, blob_pack_length, cs) {
    set_field_length(len_arg);
    assert(packlength == 4);
  }
 
  Field_vector(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
               const CHARSET_INFO *cs)
      : Field_blob(len_arg, is_nullable_arg, field_name_arg, cs, false) {
    set_field_length(len_arg);
    assert(packlength == 4);
  }
 
  Field_vector(const Field_vector &field) : Field_blob(field) {
    assert(packlength == 4);
  }
 
  void sql_type(String &res) const override {
    const CHARSET_INFO *cs = res.charset();
    size_t length =
        cs->cset->snprintf(cs, res.ptr(), res.alloced_length(), "%s(%u)",
                           "vector", get_max_dimensions());
    res.length(length);
  }
  Field_vector *clone(MEM_ROOT *mem_root) const override {
    assert(type() == MYSQL_TYPE_VECTOR);
    return new (mem_root) Field_vector(*this);
  }
  uint32 max_data_length() const override { return field_length; }
  uint32 char_length() const override { return field_length; }
  enum_field_types type() const final { return MYSQL_TYPE_VECTOR; }
  enum_field_types real_type() const final { return MYSQL_TYPE_VECTOR; }
  void make_send_field(Send_field *field) const override;
  using Field_blob::store;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  type_conversion_status store_decimal(const my_decimal *) final;
  type_conversion_status store(const char *from, size_t length,
                               const CHARSET_INFO *cs) final;
  bool eq_def(const Field *field) const override;
  uint is_equal(const Create_field *new_field) const override;
  String *val_str(String *, String *) const override;
};
 
class Field_geom final : public Field_blob {
 private:
  const std::optional<gis::srid_t> m_srid;
 
  type_conversion_status store_internal(const char *from, size_t length,
                                        const CHARSET_INFO *cs) final;
 
 public:
  enum geometry_type geom_type;
 
  Field_geom(uchar *ptr_arg, uchar *null_ptr_arg, uint null_bit_arg,
             uchar auto_flags_arg, const char *field_name_arg,
             TABLE_SHARE *share, uint blob_pack_length,
             enum geometry_type geom_type_arg, std::optional<gis::srid_t> srid)
      : Field_blob(ptr_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                   field_name_arg, share, blob_pack_length, &my_charset_bin),
        m_srid(srid),
        geom_type(geom_type_arg) {}
  Field_geom(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
             enum geometry_type geom_type_arg, std::optional<gis::srid_t> srid)
      : Field_blob(len_arg, is_nullable_arg, field_name_arg, &my_charset_bin,
                   false),
        m_srid(srid),
        geom_type(geom_type_arg) {}
  enum ha_base_keytype key_type() const final { return HA_KEYTYPE_VARBINARY2; }
  enum_field_types type() const final { return MYSQL_TYPE_GEOMETRY; }
  bool match_collation_to_optimize_range() const final { return false; }
  void sql_type(String &str) const final;
  using Field_blob::store;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  type_conversion_status store_decimal(const my_decimal *) final;
  type_conversion_status store(const char *from, size_t length,
                               const CHARSET_INFO *cs) final;
 
  /**
    Non-nullable GEOMETRY types cannot have defaults,
    but the underlying blob must still be reset.
   */
  type_conversion_status reset() final {
    type_conversion_status res = Field_blob::reset();
    if (res != TYPE_OK) return res;
    return (is_nullable() || table->is_nullable())
               ? TYPE_OK
               : TYPE_ERR_NULL_CONSTRAINT_VIOLATION;
  }
 
  geometry_type get_geometry_type() const final { return geom_type; }
  Field_geom *clone(MEM_ROOT *mem_root) const final {
    assert(type() == MYSQL_TYPE_GEOMETRY);
    return new (mem_root) Field_geom(*this);
  }
  uint is_equal(const Create_field *new_field) const final;
 
  std::optional<gis::srid_t> get_srid() const { return m_srid; }
};
 
/// A field that stores a JSON value.
class Field_json : public Field_blob {
  type_conversion_status unsupported_conversion();
  type_conversion_status store_binary(const char *ptr, size_t length);
 
 public:
  Field_json(uchar *ptr_arg, uchar *null_ptr_arg, uint null_bit_arg,
             uchar auto_flags_arg, const char *field_name_arg,
             TABLE_SHARE *share, uint blob_pack_length)
      : Field_blob(ptr_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                   field_name_arg, share, blob_pack_length, &my_charset_bin) {}
 
  Field_json(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg)
      : Field_blob(len_arg, is_nullable_arg, field_name_arg, &my_charset_bin,
                   false) {}
 
  enum_field_types type() const override { return MYSQL_TYPE_JSON; }
  void sql_type(String &str) const override;
  /**
    Return a text charset so that string functions automatically
    convert the field value to string and treat it as a non-binary
    string.
  */
  const CHARSET_INFO *charset() const override {
    return &my_charset_utf8mb4_bin;
  }
  /**
    Sort should treat the field as binary and not attempt any
    conversions.
  */
  const CHARSET_INFO *sort_charset() const final { return field_charset; }
  /**
    JSON columns don't have an associated charset. Returning false
    here prevents SHOW CREATE TABLE from attaching a CHARACTER SET
    clause to the column.
  */
  bool has_charset() const final { return false; }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) override;
  type_conversion_status store(double nr) override;
  type_conversion_status store(longlong nr, bool unsigned_val) override;
  type_conversion_status store_decimal(const my_decimal *) final;
  type_conversion_status store_json(const Json_wrapper *json);
  type_conversion_status store_time(Time_val time, uint8 dec_arg) final;
  type_conversion_status store_time(MYSQL_TIME *ltime, uint8 dec_arg) final;
  type_conversion_status store(const Field_json *field);
 
  bool pack_diff(uchar **to, ulonglong value_options) const final;
  /**
    Return the length of this field, taking into consideration that it may be in
    partial format.
 
    This is the format used when writing the binary log in row format
    and using a partial format according to
    @@session.binlog_row_value_options.
 
    @param[in] value_options The value of binlog_row_value options.
 
    @param[out] diff_vector_p If this is not NULL, the pointer it
    points to will be set to NULL if the field is to be stored in full
    format, or to the Json_diff_vector if the field is to be stored in
    partial format.
 
    @return The number of bytes needed when writing to the binlog: the
    size of the full format if stored in full format and the size of
    the diffs if stored in partial format.
  */
  longlong get_diff_vector_and_length(
      ulonglong value_options,
      const Json_diff_vector **diff_vector_p = nullptr) const;
  /**
    Return true if the before-image and after-image for this field are
    equal.
  */
  bool is_before_image_equal_to_after_image() const;
  /**
    Read the binary diff from the given buffer, and apply it to this field.
 
    @param[in,out] from Pointer to buffer where the binary diff is stored.
    This will be changed to point to the next byte after the field.
 
    @retval false Success
    @retval true Error (e.g. failed to apply the diff).  The error has
    been reported through my_error.
  */
  bool unpack_diff(const uchar **from);
 
  /**
    Retrieve the field's value as a JSON wrapper. It
    there is an error, wr is not modified and we return
    false, else true.
 
    @param[out]    wr   the JSON value
    @return true if a value is retrieved (or NULL), false if error
  */
  bool val_json(Json_wrapper *wr) const;
 
  /**
    Retrieve the JSON as an int if possible. This requires a JSON scalar
    of suitable type.
 
    @returns the JSON value as an int
  */
  longlong val_int() const final;
 
  /**
   Retrieve the JSON as a double if possible. This requires a JSON scalar
   of suitable type.
 
   @returns the JSON value as a double
   */
  double val_real() const final;
 
  /**
    Retrieve the JSON value stored in this field as text
 
    @param[in,out] buf1 string buffer for converting JSON value to string
    @param[in,out] buf2 unused
  */
  String *val_str(String *buf1, String *buf2) const final;
  my_decimal *val_decimal(my_decimal *m) const final;
  bool val_time(Time_val *time) const final;
  bool val_date(Date_val *date, my_time_flags_t flags) const final;
  bool val_datetime(Datetime_val *dt, my_time_flags_t flags) const final;
  Field_json *clone(MEM_ROOT *mem_root) const override;
  uint is_equal(const Create_field *new_field) const final;
  Item_result cast_to_int_type() const final { return INT_RESULT; }
  int cmp_binary(const uchar *a, const uchar *b,
                 uint32 max_length = ~0L) const final;
  using Field_blob::make_sort_key;
  size_t make_sort_key(uchar *to, size_t length) const override;
 
  /**
    Make a hash key that can be used by sql_executor.cc/unique_hash
    in order to support SELECT DISTINCT
 
    @param[in]  hash_val  An initial hash value.
  */
  ulonglong make_hash_key(ulonglong hash_val) const;
 
  /**
    Get a read-only pointer to the binary representation of the JSON document
    in this field.
 
    @param row_offset  Field's data offset
  */
  const char *get_binary(ptrdiff_t row_offset = 0) const;
};
 
/**
  Field that stores array of values of the same type.
 
  This Field class is used together with Item_func_array_cast class
  (CAST( .. AS .. ARRAY) function) in implementation of multi-valued index.
  Effectively it's a JSON field that contains a single JSON array. When a
  JSON value is stored, it's checked to be either a scalar, or an array.
  All source values are converted using the internal conversion field and
  stored as an array. Field_typed_array ensures that all values stored
  in the array have the same type and precision - the one specified by user.
  This way InnoDB doesn't have to do the conversion on its own and can easily
  index them.
 
  The Field_typed_array always reports type of its element and from this
  point of view it's undistinguishable from regular field having the same
  type. Due to that, fields are differentiated by is_array() property.
  Field_typed_array returns true, all other fields - false.
 
  For conversion and index applicability tests, Field_typed_array employs a
  conversion field, which is a regular Field class of array's element type.
  It's stored in the m_conv_field. All Field_typed_array::store_*() methods
  store values to the conversion field. Conversion field and typed array
  field are sharing same field_index, to allow correct read/write_set
  checks. So the field always have to be marked for read in order to allow
  read of conversions' results.
 
  @see Item_func_array_cast
*/
 
class Field_typed_array final : public Field_json {
  /// Conversion item_field
  Item_field *m_conv_item{nullptr};
  /// The array element's real type.
  enum_field_types m_elt_type;
  /// Element's decimals
  uint m_elt_decimals;
  /// Element's charset
  const CHARSET_INFO *m_elt_charset;
  const bool unsigned_flag;
 
 public:
  /**
    Constructs a Field_typed_array that is a copy of another Field_typed_array.
    @param other the other Field_typed_array object
  */
  Field_typed_array(const Field_typed_array &other);
  /**
    Constructs a Field_typed_array object.
  */
  Field_typed_array(enum_field_types elt_type, bool elt_is_unsigned,
                    size_t elt_length, uint elt_decimals, uchar *ptr_arg,
                    uchar *null_ptr_arg, uint null_bit_arg,
                    uchar auto_flags_arg, const char *field_name_arg,
                    TABLE_SHARE *share, uint blob_pack_length,
                    const CHARSET_INFO *cs);
  uint32 char_length() const override {
    return field_length / charset()->mbmaxlen;
  }
  void init(TABLE *table_arg) override;
  enum_field_types type() const override {
    return real_type_to_type(m_elt_type);
  }
  enum_field_types real_type() const override { return m_elt_type; }
  enum_field_types binlog_type() const override {
    return MYSQL_TYPE_TYPED_ARRAY;
  }
  uint32 key_length() const override;
  Field_typed_array *clone(MEM_ROOT *mem_root) const override;
  bool is_unsigned() const final { return unsigned_flag; }
  bool is_array() const override { return true; }
  Item_result result_type() const override;
  uint decimals() const override { return m_elt_decimals; }
  bool binary() const override {
    return (m_elt_type != MYSQL_TYPE_VARCHAR ||
            m_elt_charset == &my_charset_bin);
  }
  const CHARSET_INFO *charset() const override { return m_elt_charset; }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) override;
  type_conversion_status store(double nr) override;
  type_conversion_status store(longlong nr, bool unsigned_val) override;
  /**
    Store a value as an array.
    @param data   the value to store as an array
    @param array  scratch space for building the array to store
    @return the status of the operation
  */
  type_conversion_status store_array(const Json_wrapper *data,
                                     Json_array *array);
  size_t get_key_image(uchar *buff, size_t length,
                       imagetype type) const override;
  Field *new_key_field(MEM_ROOT *root, TABLE *new_table, uchar *new_ptr,
                       uchar *, uint) const override;
  /**
    These methods are used by handler to prevent returning a row past the
    end_range during range access. Since there's no order defined for sorting
    set of arrays, always return -1 here, allowing all records fetched from
    SE to be returned to server. They will be filtered by WHERE condition later.
  */
  int key_cmp(const uchar *, const uchar *) const override { return -1; }
  /**
   * @brief This function will behave similarly to MEMBER OF json operation,
   *        unlike regular key_cmp. In case of multi-valued indexes a record
   *        not matching the MEMBER OF condition indicates out of range, so the
   *        function returns 1 for not found.
   *        This definition is used in descending ref index scans.
   *        Descending index scan uses handler::ha_index_prev() function to read
   *        from the storage engine which does not compare the index key with
   *        the search key [unlike handler::ha_index_next_same()]. Hence each
   *        retrieved record needs to be validated to find a stop point. Refer
   *        key_cmp_if_same() and RefIterator<true>::Read() for more details.
   *
   * @param   key_ptr         Pointer to the key
   * @param   key_length      Key length
   * @return
   *      0   Key found in the record
   *      1   Key not found in the record
   */
  int key_cmp(const uchar *key_ptr, uint key_length) const override;
  /**
    Multi-valued index always works only as a pre-filter for actual
    condition check, and the latter always use binary collation, so no point
    to match collations in optimizer.
  */
  bool match_collation_to_optimize_range() const override { return false; }
 
  /**
    Convert arbitrary JSON value to the array's type using the conversion field.
    If conversion fails and it's not a coercion test (no_error= false) then an
    error is thrown. The converted value is guaranteed to match the field's
    type and can be indexed by SE without any additional handling.
 
    @param[in]   wr       Source data
    @param[in]   no_error Whether an error should be thrown if value can't be
                          coerced. Error should be thrown when inserting data
                          into the index, and shouldn't be thrown when the range
                          optimizer tests index applicability.
    @param[out]  coerced  The converted value. Can be nullptr if no_error is
                          true.
 
    @returns
      true   conversion failed
      false  conversion succeeded
  */
  bool coerce_json_value(const Json_wrapper *wr, bool no_error,
                         Json_wrapper *coerced) const;
 
  /**
    Get name of the index defined over this field.
 
    Since typed array fields can be created only as an underlying GC field of
    a multi-valued functional index, there's always only one index defined
    over the field.
 
    @returns
      name of the index defined over the field.
  */
  const char *get_index_name() const;
  uint32 get_length_bytes() const override {
    assert(m_elt_type == MYSQL_TYPE_VARCHAR);
    return field_length > 255 ? 2 : 1;
  }
  using Field_json::make_sort_key;
  size_t make_sort_key(uchar *to, size_t max_len) const override {
    // Not supported yet
    assert(false);
    // Dummy
    return Field_json::make_sort_key(to, max_len);
  }
  /**
    Create sort key out of given JSON value according to array's element type
 
    @param wr     JSON value to create sort key from
    @param to     buffer to create sort key in
    @param length buffer's length
 
    @returns
      actual sort key length
  */
  size_t make_sort_key(Json_wrapper *wr, uchar *to, size_t length) const;
  /**
     Save the field metadata for typed array fields.
 
     Saved metadata contains element type (1 byte) and up to 3 bytes of
     metadata - the same as each respective Field class saves
     (e.g Field_new_decimal for DECIMAL type). The only difference is that
     for VARCHAR type length is stored in 3 bytes. This allows to store longer
     strings, as its supported by JSON storage.
 
     @param   metadata_ptr   First byte of field metadata
 
     @returns number of bytes written to metadata_ptr
  */
  int do_save_field_metadata(uchar *metadata_ptr) const override;
  uint pack_length_from_metadata(uint) const override {
    return pack_length_no_ptr();
  }
  void sql_type(String &str) const final;
  void make_send_field(Send_field *field) const final;
  void set_field_index(uint16 f_index) final;
  Field *get_conv_field();
};
 
class Field_enum : public Field_str {
 protected:
  uint packlength;
 
 public:
  TYPELIB *typelib;
  Field_enum(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
             uchar null_bit_arg, uchar auto_flags_arg,
             const char *field_name_arg, uint packlength_arg,
             TYPELIB *typelib_arg, const CHARSET_INFO *charset_arg)
      : Field_str(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                  field_name_arg, charset_arg),
        packlength(packlength_arg),
        typelib(typelib_arg) {
    set_flag(ENUM_FLAG);
  }
  Field_enum(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
             uint packlength_arg, TYPELIB *typelib_arg,
             const CHARSET_INFO *charset_arg)
      : Field_enum(nullptr, len_arg,
                   is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                   field_name_arg, packlength_arg, typelib_arg, charset_arg) {}
  Field *new_field(MEM_ROOT *root, TABLE *new_table) const final;
  enum_field_types type() const final { return MYSQL_TYPE_STRING; }
  bool match_collation_to_optimize_range() const final { return false; }
  enum Item_result cmp_type() const final { return INT_RESULT; }
  enum Item_result cast_to_int_type() const final { return INT_RESULT; }
  enum ha_base_keytype key_type() const final;
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) override;
  type_conversion_status store(double nr) override;
  type_conversion_status store(longlong nr, bool unsigned_val) override;
  double val_real() const final;
  my_decimal *val_decimal(my_decimal *decimal_value) const final;
  longlong val_int() const final;
  String *val_str(String *, String *) const override;
  int cmp(const uchar *, const uchar *) const final;
  using Field_str::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final;
  uint32 pack_length() const final { return (uint32)packlength; }
  void store_type(ulonglong value);
  void sql_type(String &str) const override;
  enum_field_types real_type() const override { return MYSQL_TYPE_ENUM; }
  uint pack_length_from_metadata(uint field_metadata) const final {
    return (field_metadata & 0x00ff);
  }
  uint row_pack_length() const final { return pack_length(); }
  bool zero_pack() const override { return false; }
  bool optimize_range(uint, uint) const final { return false; }
  bool eq_def(const Field *field) const final;
  bool has_charset() const override { return true; }
  /* enum and set are sorted as integers */
  const CHARSET_INFO *sort_charset() const final { return &my_charset_bin; }
  Field_enum *clone(MEM_ROOT *mem_root) const override {
    assert(real_type() == MYSQL_TYPE_ENUM);
    return new (mem_root) Field_enum(*this);
  }
  uchar *pack(uchar *to, const uchar *from, size_t max_length) const final;
  const uchar *unpack(uchar *to, const uchar *from, uint param_data) final;
 
 private:
  int do_save_field_metadata(uchar *first_byte) const final;
  uint is_equal(const Create_field *new_field) const final;
};
 
class Field_set final : public Field_enum {
 public:
  Field_set(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
            uchar null_bit_arg, uchar auto_flags_arg,
            const char *field_name_arg, uint32 packlength_arg,
            TYPELIB *typelib_arg, const CHARSET_INFO *charset_arg)
      : Field_enum(ptr_arg, len_arg, null_ptr_arg, null_bit_arg, auto_flags_arg,
                   field_name_arg, packlength_arg, typelib_arg, charset_arg) {
    clear_flag(ENUM_FLAG);
    set_flag(SET_FLAG);
  }
  Field_set(uint32 len_arg, bool is_nullable_arg, const char *field_name_arg,
            uint32 packlength_arg, TYPELIB *typelib_arg,
            const CHARSET_INFO *charset_arg)
      : Field_set(nullptr, len_arg,
                  is_nullable_arg ? &dummy_null_buffer : nullptr, 0, NONE,
                  field_name_arg, packlength_arg, typelib_arg, charset_arg) {}
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  type_conversion_status store(double nr) final {
    if (nr < LLONG_MIN)
      return Field_set::store(static_cast<longlong>(LLONG_MIN), false);
    if (nr > LLONG_MAX_DOUBLE)
      return Field_set::store(static_cast<longlong>(LLONG_MAX), false);
    return Field_set::store(static_cast<longlong>(nr), false);
  }
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  bool zero_pack() const final { return true; }
  String *val_str(String *, String *) const final;
  void sql_type(String &str) const final;
  enum_field_types real_type() const final { return MYSQL_TYPE_SET; }
  bool has_charset() const final { return true; }
  Field_set *clone(MEM_ROOT *mem_root) const final {
    assert(real_type() == MYSQL_TYPE_SET);
    return new (mem_root) Field_set(*this);
  }
};
 
/*
  Note:
    To use Field_bit::cmp_binary() you need to copy the bits stored in
    the beginning of the record (the NULL bytes) to each memory you
    want to compare (where the arguments point).
 
    This is the reason:
    - Field_bit::cmp_binary() is only implemented in the base class
      (Field::cmp_binary()).
    - Field::cmp_binary() currently uses pack_length() to calculate how
      long the data is.
    - pack_length() includes size of the bits stored in the NULL bytes
      of the record.
*/
class Field_bit : public Field {
 public:
  uchar *bit_ptr;  // position in record where 'uneven' bits store
  uchar bit_ofs;   // offset to 'uneven' high bits
  uint bit_len;    // number of 'uneven' high bits
  uint bytes_in_rec;
  Field_bit(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
            uchar null_bit_arg, uchar *bit_ptr_arg, uchar bit_ofs_arg,
            uchar auto_flags_arg, const char *field_name_arg);
  enum_field_types type() const final { return MYSQL_TYPE_BIT; }
  enum ha_base_keytype key_type() const override { return HA_KEYTYPE_BIT; }
  uint32 max_display_length() const final { return field_length; }
  Item_result result_type() const final { return INT_RESULT; }
  type_conversion_status reset() final;
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) override;
  type_conversion_status store(double nr) final;
  type_conversion_status store(longlong nr, bool unsigned_val) final;
  type_conversion_status store_decimal(const my_decimal *) final;
  double val_real() const final;
  longlong val_int() const final;
  String *val_str(String *, String *) const final;
  bool str_needs_quotes() const final { return true; }
  my_decimal *val_decimal(my_decimal *) const final;
  int cmp(const uchar *a, const uchar *b) const final {
    assert(ptr == a || ptr == b);
    const uint cmp_len = bytes_in_rec + (bit_len != 0 ? 1 : 0);
    if (ptr == a)
      return Field_bit::key_cmp(b, cmp_len);
    else
      return -Field_bit::key_cmp(a, cmp_len);
  }
  int cmp_binary_offset(ptrdiff_t row_offset) const final {
    return cmp_offset(row_offset);
  }
  int cmp_max(const uchar *a, const uchar *b, uint max_length) const final;
  int key_cmp(const uchar *a, const uchar *b) const final {
    return cmp_binary(a, b);
  }
  int key_cmp(const uchar *str, uint length) const final;
  int cmp_offset(ptrdiff_t row_offset) const final;
  void get_image(uchar *buff, size_t length, const CHARSET_INFO *) const final {
    get_key_image(buff, length, itRAW);
  }
  void set_image(const uchar *buff, size_t length,
                 const CHARSET_INFO *cs) final {
    Field_bit::store(pointer_cast<const char *>(buff), length, cs);
  }
  size_t get_key_image(uchar *buff, size_t length, imagetype type) const final;
  void set_key_image(const uchar *buff, size_t length) final {
    Field_bit::store(pointer_cast<const char *>(buff), length, &my_charset_bin);
  }
  using Field::make_sort_key;
  size_t make_sort_key(uchar *buff, size_t length) const final {
    get_key_image(buff, length, itRAW);
    return length;
  }
  uint32 pack_length() const final { return (uint32)(field_length + 7) / 8; }
  uint32 pack_length_in_rec() const final { return bytes_in_rec; }
  uint pack_length_from_metadata(uint field_metadata) const final;
  uint row_pack_length() const final {
    return (bytes_in_rec + ((bit_len > 0) ? 1 : 0));
  }
  bool compatible_field_size(uint metadata, Relay_log_info *, uint16 mflags,
                             int *order_var) const final;
  void sql_type(String &str) const override;
  uchar *pack(uchar *to, const uchar *from, size_t max_length) const final;
  const uchar *unpack(uchar *to, const uchar *from, uint param_data) final;
  void set_default() final;
 
  Field *new_key_field(MEM_ROOT *root, TABLE *new_table, uchar *new_ptr,
                       uchar *new_null_ptr, uint new_null_bit) const final;
  void set_bit_ptr(uchar *bit_ptr_arg, uchar bit_ofs_arg) {
    bit_ptr = bit_ptr_arg;
    bit_ofs = bit_ofs_arg;
  }
  bool eq(const Field *field) const final {
    return (Field::eq(field) &&
            bit_ptr == down_cast<const Field_bit *>(field)->bit_ptr &&
            bit_ofs == down_cast<const Field_bit *>(field)->bit_ofs);
  }
  uint is_equal(const Create_field *new_field) const final;
  void move_field_offset(ptrdiff_t ptr_diff) final {
    Field::move_field_offset(ptr_diff);
    if (bit_ptr != nullptr) bit_ptr += ptr_diff;
  }
  void hash(ulong *nr, ulong *nr2) const final;
  Field_bit *clone(MEM_ROOT *mem_root) const override {
    assert(type() == MYSQL_TYPE_BIT);
    return new (mem_root) Field_bit(*this);
  }
 
 private:
  int do_save_field_metadata(uchar *first_byte) const final;
};
 
/**
  BIT field represented as chars for non-MyISAM tables.
 
  @todo The inheritance relationship is backwards since Field_bit is
  an extended version of Field_bit_as_char and not the other way
  around. Hence, we should refactor it to fix the hierarchy order.
 */
class Field_bit_as_char final : public Field_bit {
 public:
  Field_bit_as_char(uchar *ptr_arg, uint32 len_arg, uchar *null_ptr_arg,
                    uchar null_bit_arg, uchar auto_flags_arg,
                    const char *field_name_arg);
  Field_bit_as_char(uint32 len_arg, bool is_nullable_arg,
                    const char *field_name_arg)
      : Field_bit_as_char(nullptr, len_arg,
                          is_nullable_arg ? &dummy_null_buffer : nullptr, 0,
                          NONE, field_name_arg) {}
  enum ha_base_keytype key_type() const final { return HA_KEYTYPE_BINARY; }
  type_conversion_status store(const char *to, size_t length,
                               const CHARSET_INFO *charset) final;
  // Inherit the store() overloads that have not been overridden.
  using Field_bit::store;
  void sql_type(String &str) const final;
  Field_bit_as_char *clone(MEM_ROOT *mem_root) const final {
    return new (mem_root) Field_bit_as_char(*this);
  }
};
 
/// This function should only be called from legacy code.
Field *make_field(MEM_ROOT *mem_root_arg, TABLE_SHARE *share, uchar *ptr,
                  size_t field_length, uchar *null_pos, uchar null_bit,
                  enum_field_types field_type,
                  const CHARSET_INFO *field_charset,
                  Field::geometry_type geom_type, uchar auto_flags,
                  TYPELIB *interval, const char *field_name, bool is_nullable,
                  bool is_zerofill, bool is_unsigned, uint decimals,
                  bool treat_bit_as_char, uint pack_length_override,
                  std::optional<gis::srid_t> srid, bool is_array);
 
/**
  Instantiates a Field object with the given name and record buffer values.
  @param create_field The column meta data.
  @param share The table share object.
 
  @param field_name Create_field::field_name is overridden with this value
  when instantiating the Field object.
  @param field_length Create_field::length is overridden with this value
  when instantiating the Field object.
 
  @param ptr      The address of the data bytes.
  @param null_pos The address of the null bytes.
  @param null_bit The position of the column's null bit within the row's null
  bytes.
*/
Field *make_field(const Create_field &create_field, TABLE_SHARE *share,
                  const char *field_name, size_t field_length, uchar *ptr,
                  uchar *null_pos, size_t null_bit);
 
/**
  Instantiates a Field object with the given record buffer values.
  @param create_field The column meta data.
  @param share The table share object.
  @param ptr The start of the record buffer.
  @param null_pos The address of the null bytes.
 
  @param null_bit The position of the column's null bit within the row's null
  bytes.
*/
Field *make_field(const Create_field &create_field, TABLE_SHARE *share,
                  uchar *ptr, uchar *null_pos, size_t null_bit);
 
/**
  Instantiates a Field object without a record buffer.
  @param create_field The column meta data.
  @param share The table share object.
*/
Field *make_field(const Create_field &create_field, TABLE_SHARE *share);
 
/*
  A class for sending info to the client
*/
 
class Send_field {
 public:
  const char *db_name;
  const char *table_name, *org_table_name;
  const char *col_name, *org_col_name;
  ulong length;
  uint charsetnr, flags, decimals;
  enum_field_types type;
  /*
    true <=> source item is an Item_field. Needed to workaround lack of
    architecture in legacy Protocol_text implementation. Needed only for
    Protocol_classic and descendants.
  */
  bool field;
  Send_field() = default;
};
 
class Copy_field {
  /**
    Convenience definition of a copy function returned by
    get_copy_func. The parameters are:
    Copy_field*   Instance of this class. Used for accessing 'tmp' and
                  calling invoke_do_copy2().
    const Field*  Field copying from.
    Field*        Field copying to.
    Note that 'from' is 'm_to_field' if invoke_do_copy()
    is called with 'reverse' = true.
  */
  using Copy_func = void(Copy_field *, const Field *, Field *);
  Copy_func *get_copy_func();
 
 public:
  String tmp;  // For items
 
  Copy_field() = default;
 
  Copy_field(Field *to, Field *from) : Copy_field() { set(to, from); }
 
  void set(Field *to, Field *from);  // Field to field
 
 private:
  void (*m_do_copy)(Copy_field *, const Field *, Field *);
  void (*m_do_copy2)(Copy_field *, const Field *,
                     Field *);  // Used to handle null values
 
  Field *m_from_field{nullptr};
  Field *m_to_field{nullptr};
 
 public:
  void invoke_do_copy(bool reverse = false);
  void invoke_do_copy2(const Field *from_field, Field *to_field);
 
  Field *from_field() const { return m_from_field; }
 
  Field *to_field() const { return m_to_field; }
};
 
enum_field_types get_blob_type_from_length(size_t length);
size_t calc_pack_length(enum_field_types type, size_t length);
 
/**
  Calculate the length of the in-memory representation of the column from
  information which can be retrieved from dd::Column or Ha_fk_column_type
  describing it.
 
  This function calculates the amount of memory necessary to store values
  in the record buffer. It is used in cases when we want to calculate
  this value from the description of column in the form compatible with
  dd::Column without constructing full-blown Field object.
 
  @note The implementation is based on Create_field::init() and
        Create_field::create_length_to_internal_length().
 
  @param type               Column DD type.
  @param char_length        Column length as stored in DD.
  @param elements_count     Number of elements in column of ENUM/SET type.
  @param treat_bit_as_char  Indicates whether this BIT column is represented
                            as char column internally.
  @param numeric_scale      Column numeric scale as stored in DD.
  @param is_unsigned        Column unsignedness.
*/
 
size_t calc_pack_length(dd::enum_column_types type, size_t char_length,
                        size_t elements_count, bool treat_bit_as_char,
                        uint numeric_scale, bool is_unsigned);
 
uint32 calc_key_length(enum_field_types sql_type, uint32 length,
                       uint32 decimals, bool is_unsigned, uint32 elements);
type_conversion_status set_field_to_null(Field *field);
type_conversion_status set_field_to_null_with_conversions(Field *field,
                                                          bool no_conversions);
type_conversion_status store_internal_with_error_check(Field_new_decimal *field,
                                                       int conversion_err,
                                                       my_decimal *value);
 
/**
  Generate a Create_field from an Item.
 
  This function generates a Create_field from an Item by first creating a
  temporary table Field from the Item, and then creating the Create_field from
  this Field (there is currently no way to go directly from Item to
  Create_field). It is used several places:
  - In CREATE TABLE AS SELECT for creating the target table definition.
  - In functional indexes for creating the hidden generated column from the
    indexed expression.
 
  @param thd       Thread handler
  @param source_item      The item to generate a Create_field from
  @param tmp_table A table object which is used to generate a temporary table
                   field, as described above. This doesn't need to be an
                   existing table.
  @return          A Create_field generated from the input item, or nullptr
                   in case of errors.
*/
Create_field *generate_create_field(THD *thd, Item *source_item,
                                    TABLE *tmp_table);
 
inline bool is_blob(enum_field_types sql_type) {
  return (sql_type == MYSQL_TYPE_BLOB || sql_type == MYSQL_TYPE_MEDIUM_BLOB ||
          sql_type == MYSQL_TYPE_TINY_BLOB || sql_type == MYSQL_TYPE_LONG_BLOB);
}
 
/**
  @returns the expression if the input field is a hidden generated column that
  represents a functional key part. If not, return the field name. In case of
  a functional index; the expression is allocated on the THD's MEM_ROOT.
*/
const char *get_field_name_or_expression(THD *thd, const Field *field);
 
/**
  Perform per item-type checks to determine if the expression is allowed for
  a generated column, default value expression, a functional index or a check
  constraint. Note that validation of the specific function is done later in
  procedures open_table_from_share and fix_value_generator_fields.
 
  @param expression           the expression to check for validity
  @param name                 used for error reporting
  @param source               Source of value generator(a generated column, a
                              regular column with generated default value or
                              a check constraint).
  @return  false if ok, true otherwise
*/
bool pre_validate_value_generator_expr(Item *expression, const char *name,
                                       Value_generator_source source);
#endif /* FIELD_INCLUDED */