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MDEV-26938 Support descending indexes internally in InnoDB (server part)

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* preserve DESC index property in the parser
* store it in the frm (only for HA_KEY_ALG_BTREE)
* read it from the frm
* show it in SHOW CREATE
* skip DESC indexes in opt_range.cc and opt_sum.cc
* ORDER BY test

This includes a fix of MDEV-27432.
This commit is contained in:
Sergei Golubchik
2021-11-24 16:50:21 +01:00
parent 358921ce32
commit a4cac0e07a
28 changed files with 882 additions and 119 deletions
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18
sql/sql_table.cc
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@ -2281,7 +2281,7 @@ void promote_first_timestamp_column(List<Create_field> *column_definitions)
static bool key_cmp(const Key_part_spec &a, const Key_part_spec &b)
{
return a.length == b.length &&
return a.length == b.length && a.asc == b.asc &&
!lex_string_cmp(system_charset_info, &a.field_name, &b.field_name);
}
@ -3328,6 +3328,7 @@ mysql_prepare_create_table(THD *thd, HA_CREATE_INFO *create_info,
key_part_info->fieldnr= field;
key_part_info->offset= (uint16) sql_field->offset;
key_part_info->key_type=sql_field->pack_flag;
key_part_info->key_part_flag= column->asc ? 0 : HA_REVERSE_SORT;
uint key_part_length= sql_field->type_handler()->
calc_key_length(*sql_field);
@ -6335,6 +6336,14 @@ Compare_keys compare_keys_but_name(const KEY *table_key, const KEY *new_key,
return Compare_keys::NotEqual;
}
/*
Check the descending flag for index field.
*/
if ((new_part->key_part_flag ^ key_part->key_part_flag) & HA_REVERSE_SORT)
{
return Compare_keys::NotEqual;
}
auto compare= table->file->compare_key_parts(
*table->field[key_part->fieldnr - 1], new_field, *key_part, *new_part);
result= merge(result, compare);
@ -8386,9 +8395,10 @@ mysql_prepare_alter_table(THD *thd, TABLE *table,
key_part_length= 0; // Use whole field
}
key_part_length /= kfield->charset()->mbmaxlen;
key_parts.push_back(new (thd->mem_root) Key_part_spec(&cfield->field_name,
key_part_length, true),
thd->mem_root);
Key_part_spec *kps= new (thd->mem_root) Key_part_spec(&cfield->field_name,
key_part_length, true);
kps->asc= !(key_part->key_part_flag & HA_REVERSE_SORT);
key_parts.push_back(kps, thd->mem_root);
if (!(cfield->invisible == INVISIBLE_SYSTEM && cfield->vers_sys_field()))
user_keyparts= true;
}