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