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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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14
sql/handler.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
@ -91,6 +91,13 @@
#define HA_KEY_READ_ONLY 64 /* Support HA_EXTRA_KEYREAD */
/* operations for disable/enable indexes */
#define HA_KEY_SWITCH_NONUNIQ 0
#define HA_KEY_SWITCH_ALL 1
#define HA_KEY_SWITCH_NONUNIQ_SAVE 2
#define HA_KEY_SWITCH_ALL_SAVE 3
/*
Bits in index_ddl_flags(KEY *wanted_index)
for what ddl you can do with index
@ -371,8 +378,9 @@ public:
*/
virtual int restore(THD* thd, HA_CHECK_OPT* check_opt);
virtual int dump(THD* thd, int fd = -1) { return ER_DUMP_NOT_IMPLEMENTED; }
virtual int disable_indexes(bool all, bool save) { return HA_ERR_WRONG_COMMAND; }
virtual int enable_indexes() { return HA_ERR_WRONG_COMMAND; }
virtual int disable_indexes(uint mode) { return HA_ERR_WRONG_COMMAND; }
virtual int enable_indexes(uint mode) { return HA_ERR_WRONG_COMMAND; }
virtual int indexes_are_disabled(void) {return 0;}
virtual void start_bulk_insert(ha_rows rows) {}
virtual int end_bulk_insert() {return 0; }
virtual int discard_or_import_tablespace(my_bool discard) {return -1;}