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| author | Alexey Kopytov <Alexey.Kopytov@sun.com> | 2010-02-09 12:59:38 +0500 |
|---|---|---|
| committer | Alexey Kopytov <Alexey.Kopytov@sun.com> | 2010-02-09 12:59:38 +0500 |
| commit | 0888e40fa316b040cb43f6fad112a0cdcd443155 (patch) | |
| tree | 18b0423763f9cac0e0b38ba5a2175afe5f429844 /sql/sql_select.h | |
| parent | 7e0d0dd04037a626c0d984553473a1fed4b9fb56 (diff) | |
| parent | 6124451d9534b1a03e58724411c492d9de980cb4 (diff) | |
| download | mariadb-git-0888e40fa316b040cb43f6fad112a0cdcd443155.tar.gz | |
Manual merge of mysql-5.1-bugteam into mysql-trunk-merge.
Conflicts:
Text conflict in .bzr-mysql/default.conf
Text conflict in mysql-test/suite/rpl/r/rpl_slow_query_log.result
Text conflict in mysql-test/suite/rpl/t/rpl_slow_query_log.test
Conflict adding files to server-tools. Created directory.
Conflict because server-tools is not versioned, but has versioned children. Versioned directory.
Conflict adding files to server-tools/instance-manager. Created directory.
Conflict because server-tools/instance-manager is not versioned, but has versioned children. Versioned directory.
Contents conflict in server-tools/instance-manager/options.cc
Text conflict in sql/mysqld.cc
Diffstat (limited to 'sql/sql_select.h')
| -rw-r--r-- | sql/sql_select.h | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/sql/sql_select.h b/sql/sql_select.h index a84fa65a548..79758f08a69 100644 --- a/sql/sql_select.h +++ b/sql/sql_select.h @@ -361,7 +361,25 @@ public: */ bool no_const_tables; - JOIN *tmp_join; ///< copy of this JOIN to be used with temporary tables + /** + Copy of this JOIN to be used with temporary tables. + + tmp_join is used when the JOIN needs to be "reusable" (e.g. in a subquery + that gets re-executed several times) and we know will use temporary tables + for materialization. The materialization to a temporary table overwrites the + JOIN structure to point to the temporary table after the materialization is + done. This is where tmp_join is used : it's a copy of the JOIN before the + materialization and is used in restoring before re-execution by overwriting + the current JOIN structure with the saved copy. + Because of this we should pay extra care of not freeing up helper structures + that are referenced by the original contents of the JOIN. We can check for + this by making sure the "current" join is not the temporary copy, e.g. + !tmp_join || tmp_join != join + + We should free these sub-structures at JOIN::destroy() if the "current" join + has a copy is not that copy. + */ + JOIN *tmp_join; ROLLUP rollup; ///< Used with rollup bool select_distinct; ///< Set if SELECT DISTINCT |