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| author | Igor Babaev <igor@askmonty.org> | 2022-06-19 23:43:17 -0700 |
|---|---|---|
| committer | Igor Babaev <igor@askmonty.org> | 2022-06-20 16:43:44 -0700 |
| commit | 2adebf4876283859066c11f23e89965733594363 (patch) | |
| tree | c7bb7ab6f94b4d34c9adab2bab466f37b3ed7f56 /sql/sql_lex.h | |
| parent | f7d2374083184261897e86bced158d9ae2c4aaaf (diff) | |
| download | mariadb-git-bb-10.10-mdev-7487.tar.gz | |
MDEV-7487 Semi-join optimization for single-table update/delete statementsbb-10.10-mdev-7487
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>
Diffstat (limited to 'sql/sql_lex.h')
| -rw-r--r-- | sql/sql_lex.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/sql/sql_lex.h b/sql/sql_lex.h index e733b4fc53f..d1f0274136d 100644 --- a/sql/sql_lex.h +++ b/sql/sql_lex.h @@ -1642,6 +1642,8 @@ public: void lex_start(LEX *plex); bool is_unit_nest() { return (nest_flags & UNIT_NEST_FL); } void mark_as_unit_nest() { nest_flags= UNIT_NEST_FL; } + bool is_sj_conversion_prohibited(THD *thd); + bool is_sj_subselect_lifted_to_top(); }; typedef class st_select_lex SELECT_LEX; |