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WL#1687 - Optimize UNION DISTINCT ... UNION ALL (again).

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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.
This commit is contained in:
ingo@mysql.com
2004-05-06 15:53:01 +02:00
parent 4d8235b849
commit 784c9526ec
12 changed files with 530 additions and 62 deletions
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3
heap/heapdef.h
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@ -1,4 +1,4 @@
/* Copyright (C) 2000 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
@ -97,6 +97,7 @@ extern uint hp_rb_null_key_length(HP_KEYDEF *keydef, const byte *key);
extern my_bool hp_if_null_in_key(HP_KEYDEF *keyinfo, const byte *record);
extern int hp_close(register HP_INFO *info);
extern void hp_clear(HP_SHARE *info);
extern void hp_clear_keys(HP_SHARE *info);
extern uint hp_rb_pack_key(HP_KEYDEF *keydef, uchar *key, const uchar *old,
uint k_len);
#ifdef THREAD