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MDEV-18266 Changing an index comment unnecessarily rebuilds index

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ALTER_CHANGE_INDEX_COMMENT: new handler flag added

Compare_keys::EqualButComment: new outcome of compare_keys_but_name()
This commit is contained in:
Eugene Kosov
2019-07-10 21:15:12 +03:00
parent 70c2bde931
commit a0230bc76d
6 changed files with 42 additions and 7 deletions
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17
sql/sql_table.cc
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@ -6521,10 +6521,11 @@ static int compare_uint(const uint *s, const uint *t)
return (*s < *t) ? -1 : ((*s > *t) ? 1 : 0);
}
enum class Compare_keys
enum class Compare_keys : uint32_t
{
Equal,
EqualButKeyPartLength,
EqualButComment,
NotEqual
};
@ -6608,11 +6609,12 @@ Compare_keys compare_keys_but_name(const KEY *table_key, const KEY *new_key,
return Compare_keys::NotEqual;
/* Check that key comment is not changed. */
if (table_key->comment.length != new_key->comment.length ||
(table_key->comment.length &&
memcmp(table_key->comment.str, new_key->comment.str,
table_key->comment.length) != 0))
return Compare_keys::NotEqual;
if (cmp(table_key->comment, new_key->comment) != 0)
{
if (result != Compare_keys::Equal)
return Compare_keys::NotEqual;
result= Compare_keys::EqualButComment;
}
return result;
}
@ -7002,6 +7004,9 @@ static bool fill_alter_inplace_info(THD *thd, TABLE *table, bool varchar,
case Compare_keys::EqualButKeyPartLength:
ha_alter_info->handler_flags|= ALTER_COLUMN_INDEX_LENGTH;
continue;
case Compare_keys::EqualButComment:
ha_alter_info->handler_flags|= ALTER_CHANGE_INDEX_COMMENT;
continue;
case Compare_keys::NotEqual:
break;
}