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| author | ingo@mysql.com <> | 2004-05-06 15:53:01 +0200 |
|---|---|---|
| committer | ingo@mysql.com <> | 2004-05-06 15:53:01 +0200 |
| commit | 784c9526ecb1f19216bdbb7a24fd85d71529ad5f (patch) | |
| tree | 7facff5ed1695a7cdb0e0ab674137605074739d9 /sql/sql_select.cc | |
| parent | 4d8235b8490155876208fb9c8328d5900b7a42ca (diff) | |
| download | mariadb-git-784c9526ecb1f19216bdbb7a24fd85d71529ad5f.tar.gz | |
WL#1687 - Optimize UNION DISTINCT ... UNION ALL (again).
HEAP: Copies the key count to a backup variable and sets the key count to zero.
That way, no HEAP function will ever try to touch any index.
Re-enabling is done by copying back the backup variable.
To avoid memory leak at table close, disable deletes all index trees.
Re-enabling must be done with empty indexes and data anyway. Otherwise,
the indexes would need to be repaired, wich HEAP is not capable of.
MyISAM: Only the key_map is cleared and set.
Re-enabling must be done with empty indexes and data. Otherwise, repair needs
to be done which will enable all keys persistently.
The former implementation disabled only non-unique keys and maked this persistent.
The new implementation additionally can disable all keys, but only without
making this persistent. Re-enabling all keys can be done without repair,
if data file and indexes are empty.
Diffstat (limited to 'sql/sql_select.cc')
| -rw-r--r-- | sql/sql_select.cc | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/sql/sql_select.cc b/sql/sql_select.cc index ffc52817322..f8347b9342f 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -1,4 +1,4 @@ -/* Copyright (C) 2000-2003 MySQL AB & MySQL Finland AB & TCX DataKonsult AB +/* Copyright (C) 2000-2004 MySQL AB & MySQL Finland AB & TCX DataKonsult AB This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -5545,6 +5545,8 @@ bool create_myisam_from_heap(THD *thd, TABLE *table, TMP_TABLE_PARAM *param, goto err2; if (open_tmp_table(&new_table)) goto err1; + if (table->file->indexes_are_disabled()) + new_table.file->disable_indexes(HA_KEY_SWITCH_ALL); table->file->index_end(); table->file->rnd_init(); if (table->no_rows) |