database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-29 05:21:33 +03:00
Code Activity

MDEV-7487 Semi-join optimization for single-table update/delete statements

Browse Source 
This patch allows to use semi-join optimization at the top level of
single-table update and delete statements.
The problem of supporting such optimization became easy to resolve after
processing a single-table update/delete statement started using JOIN
structure. This allowed to use JOIN::prepare() not only for multi-table
updates/deletes but for single-table ones as well. This was done in the
patch for mdev-28883:
Re-design the upper level of handling UPDATE and DELETE statements.

Note that JOIN::prepare() detects all subqueries that can be considered
as candidates for semi-join optimization. The code added by this patch
looks for such candidates at the top level and if such candidates are found
in the processed single-table update/delete the statement is handled in
the same way as a multi-table update/delete.

    Approved by Oleksandr Byelkin <sanja@mariadb.com>
This commit is contained in:
Igor Babaev
2023-01-09 22:39:39 -08:00
parent e2e3524d72
commit 554278e24d
14 changed files with 6198 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
sql/sql_update.cc
View File

@ -382,7 +382,6 @@ bool Sql_cmd_update::update_single_table(THD *thd)
DBUG_ENTER("Sql_cmd_update::update_single_table");
THD_STAGE_INFO(thd, stage_init_update);
create_explain_query(thd->lex, thd->mem_root);
thd->table_map_for_update= 0;
@ -2479,6 +2478,8 @@ int multi_update::do_updates()
table = cur_table->table;
if (table == table_to_update)
continue; // Already updated
if (table->file->pushed_rowid_filter)
table->file->disable_pushed_rowid_filter();
org_updated= updated;
tmp_table= tmp_tables[cur_table->shared];
tmp_table->file->extra(HA_EXTRA_CACHE); // Change to read cache
@ -2673,7 +2674,8 @@ int multi_update::do_updates()
check_opt_it.rewind();
while (TABLE *tbl= check_opt_it++)
tbl->file->ha_rnd_end();
if (table->file->save_pushed_rowid_filter)
table->file->enable_pushed_rowid_filter();
}
DBUG_RETURN(0);
@ -2684,6 +2686,8 @@ err:
}
err2:
if (table->file->save_pushed_rowid_filter)
table->file->enable_pushed_rowid_filter();
if (table->file->inited)
(void) table->file->ha_rnd_end();
if (tmp_table->file->inited)
@ -2987,7 +2991,9 @@ bool Sql_cmd_update::prepare_inner(THD *thd)
{
goto err;
}
if (!multitable &&
select_lex->sj_subselects.elements)
multitable= true;
}
if (table_list->has_period())