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/* Copyright (C) 2003, 2005 MySQL 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
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
Preload indexes into key cache
*/
#include "myisamdef.h"
/*
Preload pages of the index file for a table into the key cache
SYNOPSIS
mi_preload()
info open table
map map of indexes to preload into key cache
ignore_leaves only non-leaves pages are to be preloaded
RETURN VALUE
0 if a success. error code - otherwise.
NOTES.
At present pages for all indexes are preloaded.
In future only pages for indexes specified in the key_map parameter
of the table will be preloaded.
*/
int mi_preload(MI_INFO *info, ulonglong key_map, my_bool ignore_leaves)
{
uint i;
ulong length, block_length= 0;
uchar *buff= NULL;
MYISAM_SHARE* share= info->s;
uint keys= share->state.header.keys;
MI_KEYDEF *keyinfo= share->keyinfo;
my_off_t key_file_length= share->state.state.key_file_length;
my_off_t pos= share->base.keystart;
DBUG_ENTER("mi_preload");
if (!keys || !mi_is_any_key_active(key_map) || key_file_length == pos)
DBUG_RETURN(0);
block_length= keyinfo[0].block_length;
if (ignore_leaves)
{
/* Check whether all indexes use the same block size */
for (i= 1 ; i < keys ; i++)
{
if (keyinfo[i].block_length != block_length)
DBUG_RETURN(my_errno= HA_ERR_NON_UNIQUE_BLOCK_SIZE);
}
}
else
block_length= share->key_cache->key_cache_block_size;
length= info->preload_buff_size/block_length * block_length;
set_if_bigger(length, block_length);
if (!(buff= (uchar *) my_malloc(length, MYF(MY_WME))))
DBUG_RETURN(my_errno= HA_ERR_OUT_OF_MEM);
if (flush_key_blocks(share->key_cache,share->kfile, FLUSH_RELEASE))
goto err;
do
{
/* Read the next block of index file into the preload buffer */
if ((my_off_t) length > (key_file_length-pos))
length= (ulong) (key_file_length-pos);
if (my_pread(share->kfile, (uchar*) buff, length, pos, MYF(MY_FAE|MY_FNABP)))
goto err;
if (ignore_leaves)
{
uchar *end= buff+length;
do
{
if (mi_test_if_nod(buff))
{
if (key_cache_insert(share->key_cache,
share->kfile, pos, DFLT_INIT_HITS,
(uchar*) buff, block_length))
goto err;
}
pos+= block_length;
}
while ((buff+= block_length) != end);
buff= end-length;
}
else
{
if (key_cache_insert(share->key_cache,
share->kfile, pos, DFLT_INIT_HITS,
(uchar*) buff, length))
goto err;
pos+= length;
}
}
while (pos != key_file_length);
my_free((char*) buff, MYF(0));
DBUG_RETURN(0);
err:
my_free((char*) buff, MYF(MY_ALLOW_ZERO_PTR));
DBUG_RETURN(my_errno= errno);
}
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