range_optimizer.h

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/* Copyright (c) 2000, 2024, Oracle and/or its affiliates.
 
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   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
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   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
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   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
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
/* classes to use when handling where clause */
 
#ifndef SQL_RANGE_OPTIMIZER_RANGE_OPTIMIZER_H_
#define SQL_RANGE_OPTIMIZER_RANGE_OPTIMIZER_H_
 
#include <assert.h>
#include <sys/types.h>
#include <algorithm>
 
#include "my_base.h"
#include "my_inttypes.h"
#include "my_table_map.h"
#include "prealloced_array.h"  // Prealloced_array
#include "sql/field.h"         // Field
#include "sql/handler.h"
#include "sql/item_func.h"
#include "sql/iterators/row_iterator.h"
#include "sql/key_spec.h"
#include "sql/malloc_allocator.h"  // IWYU pragma: keep
#include "sql/sql_bitmap.h"
#include "sql/sql_const.h"
#include "sql_string.h"
 
class Item;
class Opt_trace_context;
class Query_block;
class RANGE_OPT_PARAM;
class THD;
struct MY_BITMAP;
struct TABLE;
 
struct KEY_PART {
  uint16 key, part;
  /* See KEY_PART_INFO for meaning of the next two: */
  uint16 store_length, length;
  uint8 null_bit;
  /*
    Keypart flags (0 when this structure is used by partition pruning code
    for fake partitioning index description)
  */
  uint16 flag;
  Field *field;
  Field::imagetype image_type;
};
 
class QUICK_RANGE {
 public:
  uchar *min_key, *max_key;
  uint16 min_length, max_length;
 
  /// Stores bitwise-or'ed bits defined in enum key_range_flags.
  uint16 flag;
 
  /**
    Stores one of the HA_READ_MBR_XXX items in enum ha_rkey_function, only
    effective when flag has a GEOM_FLAG bit.
  */
  enum ha_rkey_function rkey_func_flag;
  key_part_map min_keypart_map,  // bitmap of used keyparts in min_key
      max_keypart_map;           // bitmap of used keyparts in max_key
 
  QUICK_RANGE(); /* Full range */
  QUICK_RANGE(MEM_ROOT *mem_root, const uchar *min_key_arg, uint min_length_arg,
              key_part_map min_keypart_map_arg, const uchar *max_key_arg,
              uint max_length_arg, key_part_map max_keypart_map_arg,
              uint flag_arg, enum ha_rkey_function rkey_func);
 
  /**
     Initializes a key_range object for communication with storage engine.
 
     This function facilitates communication with the Storage Engine API by
     translating the minimum endpoint of the interval represented by this
     QUICK_RANGE into an index range endpoint specifier for the engine.
 
     @param kr Pointer to an uninitialized key_range C struct.
 
     @param prefix_length The length of the search key prefix to be used for
     lookup.
 
     @param keypart_map A set (bitmap) of keyparts to be used.
  */
  void make_min_endpoint(key_range *kr, uint prefix_length,
                         key_part_map keypart_map) {
    make_min_endpoint(kr);
    kr->length = std::min(kr->length, prefix_length);
    kr->keypart_map &= keypart_map;
  }
 
  /**
     Initializes a key_range object for communication with storage engine.
 
     This function facilitates communication with the Storage Engine API by
     translating the minimum endpoint of the interval represented by this
     QUICK_RANGE into an index range endpoint specifier for the engine.
 
     @param kr Pointer to an uninitialized key_range C struct.
  */
  void make_min_endpoint(key_range *kr) {
    kr->key = (const uchar *)min_key;
    kr->length = min_length;
    kr->keypart_map = min_keypart_map;
    kr->flag = ((flag & NEAR_MIN)   ? HA_READ_AFTER_KEY
                : (flag & EQ_RANGE) ? HA_READ_KEY_EXACT
                                    : HA_READ_KEY_OR_NEXT);
  }
 
  /**
     Initializes a key_range object for communication with storage engine.
 
     This function facilitates communication with the Storage Engine API by
     translating the maximum endpoint of the interval represented by this
     QUICK_RANGE into an index range endpoint specifier for the engine.
 
     @param kr Pointer to an uninitialized key_range C struct.
 
     @param prefix_length The length of the search key prefix to be used for
     lookup.
 
     @param keypart_map A set (bitmap) of keyparts to be used.
  */
  void make_max_endpoint(key_range *kr, uint prefix_length,
                         key_part_map keypart_map) {
    make_max_endpoint(kr);
    kr->length = std::min(kr->length, prefix_length);
    kr->keypart_map &= keypart_map;
  }
 
  /**
     Initializes a key_range object for communication with storage engine.
 
     This function facilitates communication with the Storage Engine API by
     translating the maximum endpoint of the interval represented by this
     QUICK_RANGE into an index range endpoint specifier for the engine.
 
     @param kr Pointer to an uninitialized key_range C struct.
  */
  void make_max_endpoint(key_range *kr) {
    kr->key = (const uchar *)max_key;
    kr->length = max_length;
    kr->keypart_map = max_keypart_map;
    /*
      We use READ_AFTER_KEY here because if we are reading on a key
      prefix we want to find all keys with this prefix
    */
    kr->flag = (flag & NEAR_MAX ? HA_READ_BEFORE_KEY : HA_READ_AFTER_KEY);
  }
};
 
using Quick_ranges = Mem_root_array<QUICK_RANGE *>;
using Quick_ranges_array = Mem_root_array<Quick_ranges *>;
 
bool setup_range_optimizer_param(THD *thd, MEM_ROOT *return_mem_root,
                                 MEM_ROOT *temp_mem_root, Key_map keys_to_use,
                                 TABLE *table, Query_block *query_block,
                                 RANGE_OPT_PARAM *param);
 
int test_quick_select(THD *thd, MEM_ROOT *return_mem_root,
                      MEM_ROOT *temp_mem_root, Key_map keys_to_use,
                      table_map prev_tables, table_map read_tables,
                      ha_rows limit, bool force_quick_range,
                      const enum_order interesting_order, TABLE *table,
                      bool skip_records_in_range, Item *cond,
                      Key_map *needed_reg, bool ignore_table_scan,
                      Query_block *query_block, AccessPath **path);
 
void store_key_image_to_rec(Field *field, uchar *ptr, uint len);
 
extern String null_string;
 
/// Global initialization of the null_element. Call on server start.
void range_optimizer_init();
 
/// Global destruction of the null_element. Call on server stop.
void range_optimizer_free();
 
/**
  Test if 'value' is comparable to 'field' when setting up range
  access for predicate "field OP value". 'field' is a field in the
  table being optimized for while 'value' is whatever 'field' is
  compared to.
 
  @param cond_func   the predicate item that compares 'field' with 'value'
  @param field       field in the predicate
  @param itype       itMBR if indexed field is spatial, itRAW otherwise
  @param comp_type   comparator for the predicate
  @param value       whatever 'field' is compared to
 
  @return true if 'field' and 'value' are comparable, false otherwise
*/
 
bool comparable_in_index(Item *cond_func, const Field *field,
                         const Field::imagetype itype,
                         Item_func::Functype comp_type, const Item *value);
 
void trace_quick_description(const AccessPath *path, Opt_trace_context *trace);
 
#endif  // SQL_RANGE_OPTIMIZER_RANGE_OPTIMIZER_H_