rem0wrec.h

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/** @file include/rem0wrec.h
 Record manager wrapper declaration.
 
 After INSTANT ADD/DROP feature, fields index on logical record might not be
 same as field index on physical record. So this wrapper is implemented which
 translates logical index to physical index. And then functions of low level
 record manager (rem0lrec.h) are called with physical index of the field.
 
 Created 13/08/2021 Mayank Prasad
******************************************************************************/
 
#ifndef rem0wrec_h
#define rem0wrec_h
 
#include "rem/rec.h"
 
const byte *rec_get_nth_field_old(const dict_index_t *index, const rec_t *rec,
                                  ulint n, ulint *len);
 
/** The following function is used to get an offset to the nth data field in a
record.
@param[in]      index   record descriptor
@param[in]      offsets array returned by rec_get_offsets()
@param[in]      n       index of the field
@param[out]     len     length of the field; UNIV_SQL_NULL if SQL null;
                        UNIV_SQL_ADD_COL_DEFAULT if it's default value and no
                        value inlined
@note This long method is made inline because it is on performance sensitive hot
path. One must run performance tests if they intend to improve this method.
@return offset from the origin of rec */
inline ulint rec_get_nth_field_offs(const dict_index_t *index,
                                    const ulint *offsets, ulint n, ulint *len) {
  if (index && index->has_row_versions()) {
    n = index->get_field_off_pos(n);
  }
 
  ulint offs;
  ulint length;
  ut_ad(n < rec_offs_n_fields(offsets));
  ut_ad(len);
 
  if (n == 0) {
    offs = 0;
  } else {
    offs = rec_offs_base(offsets)[n] & REC_OFFS_MASK;
  }
 
  length = rec_offs_base(offsets)[1 + n];
 
  if (length & REC_OFFS_SQL_NULL) {
    length = UNIV_SQL_NULL;
  } else if (length & REC_OFFS_DEFAULT) {
    length = UNIV_SQL_ADD_COL_DEFAULT;
  } else if (length & REC_OFFS_DROP) {
    length = UNIV_SQL_INSTANT_DROP_COL;
  } else {
    length &= REC_OFFS_MASK;
    length -= offs;
  }
 
  *len = length;
  return (offs);
}
 
/** Gets the value of the specified field in the record.
@param[in]      index   record descriptor
@param[in]      rec     physical record
@param[in]      offsets array returned by rec_get_offsets()
@param[in]      n       index of the field
@param[out]     len     length of the field, UNIV_SQL_NULL if SQL null
@return value of the field */
inline const byte *rec_get_nth_field(const dict_index_t *index,
                                     const rec_t *rec, const ulint *offsets,
                                     ulint n, ulint *len) {
  return rec + rec_get_nth_field_offs(index, offsets, n, len);
}
 
/** Gets the value of the specified field in the record.
@param[in]      index   record descriptor
@param[in]      rec     physical record
@param[in]      offsets array returned by rec_get_offsets()
@param[in]      n       index of the field
@param[out]     len     length of the field, UNIV_SQL_NULL if SQL null
@return value of the field */
inline byte *rec_get_nth_field(const dict_index_t *index, rec_t *rec,
                               const ulint *offsets, ulint n, ulint *len) {
  return const_cast<byte *>(rec_get_nth_field(
      index, const_cast<const rec_t *>(rec), offsets, n, len));
}
 
/** The following function is used to get the offset to the nth
data field in an old-style record.
@param[in]      index   record descriptor
@param[in]      rec     record
@param[in]      n       index of the field
@param[in]      len     length of the field;UNIV_SQL_NULL if SQL null
@return offset to the field */
ulint rec_get_nth_field_offs_old(const dict_index_t *index, const rec_t *rec,
                                 ulint n, ulint *len);
 
/** Validates offset and field number.
@param[in]      index   record descriptor
@param[in]      offsets array returned by rec_get_offsets()
@param[in]      n       nth field
@param[in]      L       Line number of calling satement*/
void validate_rec_offset(const dict_index_t *index, const ulint *offsets,
                         ulint n, ut::Location L);
 
/** Returns nonzero if the extern bit is set in nth field of rec.
@param[in]      index           record descriptor
@param[in]      offsets         array returned by rec_get_offsets()
@param[in]      n               nth field
@return nonzero if externally stored */
[[nodiscard]] inline ulint rec_offs_nth_extern(const dict_index_t *index,
                                               const ulint *offsets, ulint n) {
  if (index && index->has_row_versions()) {
    n = index->get_field_off_pos(n);
  }
 
  validate_rec_offset(index, offsets, n, UT_LOCATION_HERE);
  /* Returns nonzero if the extern bit is set in nth field of rec. */
  return rec_offs_base(offsets)[1 + n] & REC_OFFS_EXTERNAL;
}
 
/** Mark the nth field as externally stored.
@param[in]      index           record descriptor
@param[in]      offsets         array returned by rec_get_offsets()
@param[in]      n               nth field */
void rec_offs_make_nth_extern(dict_index_t *index, ulint *offsets, ulint n);
 
/** Returns nonzero if the SQL NULL bit is set in nth field of rec.
@param[in]      index           record descriptor
@param[in]      offsets         array returned by rec_get_offsets()
@param[in]      n               nth field
@return nonzero if SQL NULL */
[[nodiscard]] ulint rec_offs_nth_sql_null(const dict_index_t *index,
                                          const ulint *offsets, ulint n);
 
/** Returns nonzero if the default bit is set in nth field of rec.
@param[in]      index           record descriptor
@param[in]      offsets         array returned by rec_get_offsets()
@param[in]      n               nth field
@return nonzero if default bit is set */
ulint rec_offs_nth_default(const dict_index_t *index, const ulint *offsets,
                           ulint n);
 
/** Gets the physical size of a field.
@param[in]      index           record descriptor
@param[in]      offsets         array returned by rec_get_offsets()
@param[in]      n               nth field
@return length of field */
[[nodiscard]] ulint rec_offs_nth_size(const dict_index_t *index,
                                      const ulint *offsets, ulint n);
 
/** This is used to modify the value of an already existing field in a record.
The previous value must have exactly the same size as the new value. If len is
UNIV_SQL_NULL then the field is treated as an SQL null.
For records in ROW_FORMAT=COMPACT (new-style records), len must not be
UNIV_SQL_NULL unless the field already is SQL null.
@param[in]      index   record descriptor
@param[in]      rec     record
@param[in]      offsets array returned by rec_get_offsets()
@param[in]      n       index number of the field
@param[in]      len     length of the data or UNIV_SQL_NULL.
                        If not SQL null, must have the same length as the
                        previous value.
                        If SQL null, previous value must be SQL null.
@param[in]      data    pointer to the data if not SQL null */
void rec_set_nth_field(const dict_index_t *index, rec_t *rec,
                       const ulint *offsets, ulint n, const void *data,
                       ulint len);
 
/** Returns nonzero if the field is stored off-page.
@param[in]      index   index
@param[in]      rec     record
@param[in]      n       field index
@retval 0 if the field is stored in-page
@retval REC_2BYTE_EXTERN_MASK if the field is stored externally */
[[nodiscard]] ulint rec_2_is_field_extern(const dict_index_t *index,
                                          const rec_t *rec, ulint n);
 
/** The following function returns the data size of an old-style physical
record, that is the sum of field lengths. SQL null fields are counted as length
0 fields. The value returned by the function is the distance from record origin
to record end in bytes.
@return size */
ulint rec_get_data_size_old(const rec_t *rec);
#endif