myrg_rkey.c
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:3k
- /* Copyright (C) 2000 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
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
- 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 */
- /* Read record based on a key */
- /*
- * HA_READ_KEY_EXACT => SEARCH_BIGGER
- * HA_READ_KEY_OR_NEXT => SEARCH_BIGGER
- * HA_READ_AFTER_KEY => SEARCH_BIGGER
- * HA_READ_PREFIX => SEARCH_BIGGER
- * HA_READ_KEY_OR_PREV => SEARCH_SMALLER
- * HA_READ_BEFORE_KEY => SEARCH_SMALLER
- * HA_READ_PREFIX_LAST => SEARCH_SMALLER
- */
- #include "myrg_def.h"
- /* todo: we could store some additional info to speedup lookups:
- column (key, keyseg) can be constant per table
- it can also be increasing (table1.val > table2.val > ...),
- or decreasing, <=, >=, etc.
- SerG
- */
- int myrg_rkey(MYRG_INFO *info,byte *buf,int inx, const byte *key,
- uint key_len, enum ha_rkey_function search_flag)
- {
- byte *key_buff;
- uint pack_key_length;
- MYRG_TABLE *table;
- MI_INFO *mi;
- int err;
- DBUG_ENTER("myrg_rkey");
- LINT_INIT(key_buff);
- LINT_INIT(pack_key_length);
- if (_myrg_init_queue(info,inx,search_flag))
- DBUG_RETURN(my_errno);
- for (table=info->open_tables ; table != info->end_table ; table++)
- {
- mi=table->table;
- if (table == info->open_tables)
- {
- err=mi_rkey(mi,0,inx,key,key_len,search_flag);
- /* Get the saved packed key and packed key length. */
- key_buff=(byte*) mi->lastkey+mi->s->base.max_key_length;
- pack_key_length=mi->pack_key_length;
- }
- else
- {
- mi->once_flags|= USE_PACKED_KEYS;
- err=mi_rkey(mi,0,inx,key_buff,pack_key_length,search_flag);
- }
- info->last_used_table=table+1;
- if (err)
- {
- if (err == HA_ERR_KEY_NOT_FOUND)
- continue;
- DBUG_PRINT("exit", ("err: %d", err));
- DBUG_RETURN(err);
- }
- /* adding to queue */
- queue_insert(&(info->by_key),(byte *)table);
- }
- DBUG_PRINT("info", ("tables with matches: %u", info->by_key.elements));
- if (!info->by_key.elements)
- DBUG_RETURN(HA_ERR_KEY_NOT_FOUND);
- mi=(info->current_table=(MYRG_TABLE *)queue_top(&(info->by_key)))->table;
- mi->once_flags|= RRND_PRESERVE_LASTINX;
- DBUG_PRINT("info", ("using table no: %d",
- info->current_table - info->open_tables + 1));
- DBUG_DUMP("result key", (byte*) mi->lastkey, mi->lastkey_length);
- DBUG_RETURN(_myrg_mi_read_record(mi,buf));
- }