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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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145
heap/hp_clear.c
View File

@ -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
@ -29,13 +29,60 @@ void heap_clear(HP_INFO *info)
void hp_clear(HP_SHARE *info)
{
uint key;
DBUG_ENTER("hp_clear");
if (info->block.levels)
VOID(hp_free_level(&info->block,info->block.levels,info->block.root,
(byte*) 0));
info->block.levels=0;
hp_clear_keys(info);
info->records=info->deleted=info->data_length=0;
info->blength=1;
info->changed=0;
info->del_link=0;
DBUG_VOID_RETURN;
}
/*
Clear all keys.
SYNOPSIS
heap_clear_keys()
info A pointer to the heap storage engine HP_INFO struct.
DESCRIPTION
Delete all trees of all indexes and leave them empty.
RETURN
void
*/
void heap_clear_keys(HP_INFO *info)
{
hp_clear(info->s);
}
/*
Clear all keys.
SYNOPSIS
hp_clear_keys()
info A pointer to the heap storage engine HP_SHARE struct.
DESCRIPTION
Delete all trees of all indexes and leave them empty.
RETURN
void
*/
void hp_clear_keys(HP_SHARE *info)
{
uint key;
DBUG_ENTER("hp_clear_keys");
for (key=0 ; key < info->keys ; key++)
{
HP_KEYDEF *keyinfo = info->keydef + key;
@ -52,9 +99,95 @@ void hp_clear(HP_SHARE *info)
block->last_allocated=0;
}
}
info->records=info->deleted=info->data_length=info->index_length=0;
info->blength=1;
info->changed=0;
info->del_link=0;
info->index_length=0;
DBUG_VOID_RETURN;
}
/*
Disable all indexes.
SYNOPSIS
heap_disable_indexes()
info A pointer to the heap storage engine HP_INFO struct.
DESCRIPTION
Disable and clear (remove contents of) all indexes.
RETURN
0 ok
*/
int heap_disable_indexes(HP_INFO *info)
{
HP_SHARE *share= info->s;
if (share->keys)
{
hp_clear_keys(share);
share->currently_disabled_keys= share->keys;
share->keys= 0;
}
return 0;
}
/*
Enable all indexes
SYNOPSIS
heap_enable_indexes()
info A pointer to the heap storage engine HP_INFO struct.
DESCRIPTION
Enable all indexes. The indexes might have been disabled
by heap_disable_index() before.
The function works only if both data and indexes are empty,
since the heap storage engine cannot repair the indexes.
To be sure, call handler::delete_all_rows() before.
RETURN
0 ok
HA_ERR_CRASHED data or index is non-empty.
*/
int heap_enable_indexes(HP_INFO *info)
{
int error= 0;
HP_SHARE *share= info->s;
if (share->data_length || share->index_length)
error= HA_ERR_CRASHED;
else
if (share->currently_disabled_keys)
{
share->keys= share->currently_disabled_keys;
share->currently_disabled_keys= 0;
}
return error;
}
/*
Test if indexes are disabled.
SYNOPSIS
heap_indexes_are_disabled()
info A pointer to the heap storage engine HP_INFO struct.
DESCRIPTION
Test if indexes are disabled.
RETURN
0 indexes are not disabled
1 all indexes are disabled
[2 non-unique indexes are disabled - NOT YET IMPLEMENTED]
*/
int heap_indexes_are_disabled(HP_INFO *info)
{
HP_SHARE *share= info->s;
return (! share->keys && share->currently_disabled_keys);
}