Hi, Alexander,
On Jan 11, Alexander Barkov wrote:
> revision-id: 424ee6eac78 (mariadb-10.5.23-57-g424ee6eac78)
> parent(s): c9902a20b3a
> author: Alexander Barkov
> committer: Alexander Barkov
> timestamp: 2024-01-10 15:35:25 +0400
> message:
>
> MDEV-32837 long unique does not work like unique key when using replace
>
> diff --git a/sql/sql_insert.cc b/sql/sql_insert.cc
> index ec9e379768f..edc2be207f3 100644
> --- a/sql/sql_insert.cc
> +++ b/sql/sql_insert.cc
> @@ -2065,7 +2065,8 @@ int write_record(THD *thd, TABLE *table, COPY_INFO
> *info, select_result *sink)
> we just should not expose this fact to users by invoking
> ON UPDATE triggers.
> */
> - if (last_uniq_key(table,key_nr) &&
> + if ((!table->s->long_unique_table || table->versioned()) &&
> + last_uniq_key(table,key_nr) &&
> !table->file->referenced_by_foreign_key() &&
> (!table->triggers || !table->triggers->has_delete_triggers()))
> {
1. why table->versioned() ?
2. use show status in your test for handler_update/delete to see what
REPLACE actually did
3. technically, you can keep the optimization if the long unique is the
last *and there are no in-engine uniques*, this can be checked with
&& !(table->key_info->flags & HA_NOSAME)
4. but here's the problem that last_uniq_key() doesn't see long uniques,
so it'll treat every one of them as the last. So it should be
something like
bool is_long_unique= table->s->key_info[key_nr].flags & HA_UNIQUE_HASH;
if ((is_long_unique ? last_uniq_key(table, table->s->key_info, key_nr)
&&
!(table->key_info->flags & HA_NOSAME)
: last_uniq_key(table, table->key_info, key_nr)) &&
!table->file->referenced_by_foreign_key() &&
(!table->triggers || !table->triggers->has_delete_triggers()))
I suspect this will correctly use the UPDATE optimization in all cases
(only long unique / mix of uniques)x(last / not last key conflicting)
Regards,
Sergei
Chief Architect, MariaDB Server
and secur...@mariadb.org
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