/* Copyright (C) 2000-2006 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 */ /* Read record based on a key */ #include "myisamdef.h" /* Read a record using key */ /* Ordinary search_flag is 0 ; Give error if no record with key */ int mi_rkey(MI_INFO *info, uchar *buf, int inx, const uchar *key, key_part_map keypart_map, enum ha_rkey_function search_flag) { uchar *key_buff; MYISAM_SHARE *share=info->s; MI_KEYDEF *keyinfo; HA_KEYSEG *last_used_keyseg; uint pack_key_length, use_key_length, nextflag; uint myisam_search_flag; int res= 0; DBUG_ENTER("mi_rkey"); DBUG_PRINT("enter", ("base: 0x%lx buf: 0x%lx inx: %d search_flag: %d", (long) info, (long) buf, inx, search_flag)); if ((inx = _mi_check_index(info,inx)) < 0) DBUG_RETURN(my_errno); info->update&= (HA_STATE_CHANGED | HA_STATE_ROW_CHANGED); info->last_key_func= search_flag; keyinfo= share->keyinfo + inx; if (info->once_flags & USE_PACKED_KEYS) { info->once_flags&= ~USE_PACKED_KEYS; /* Reset flag */ /* key is already packed!; This happens when we are using a MERGE TABLE In this key 'key_part_map' is the length of the key ! */ key_buff=info->lastkey+info->s->base.max_key_length; pack_key_length= keypart_map; bmove(key_buff, key, pack_key_length); last_used_keyseg= info->s->keyinfo[inx].seg + info->last_used_keyseg; } else { DBUG_ASSERT(keypart_map); /* Save the packed key for later use in the second buffer of lastkey. */ key_buff=info->lastkey+info->s->base.max_key_length; pack_key_length=_mi_pack_key(info,(uint) inx, key_buff, (uchar*) key, keypart_map, &last_used_keyseg); /* Save packed_key_length for use by the MERGE engine. */ info->pack_key_length= pack_key_length; info->last_used_keyseg= (uint16) (last_used_keyseg - info->s->keyinfo[inx].seg); DBUG_EXECUTE("key",_mi_print_key(DBUG_FILE, keyinfo->seg, key_buff, pack_key_length);); } if (fast_mi_readinfo(info)) goto err; if (share->concurrent_insert) rw_rdlock(&share->key_root_lock[inx]); nextflag=myisam_read_vec[search_flag]; use_key_length=pack_key_length; if (!(nextflag & (SEARCH_FIND | SEARCH_NO_FIND | SEARCH_LAST))) use_key_length=USE_WHOLE_KEY; switch (info->s->keyinfo[inx].key_alg) { case HA_KEY_ALG_BTREE: default: myisam_search_flag= myisam_read_vec[search_flag]; if (!_mi_search(info, keyinfo, key_buff, use_key_length, myisam_search_flag, info->s->state.key_root[inx])) { /* Found a key, but it might not be usable. We cannot use rows that are inserted by other threads after we got our table lock ("concurrent inserts"). The record may not even be present yet. Keys are inserted into the index(es) before the record is inserted into the data file. When we got our table lock, we saved the current data_file_length. Concurrent inserts always go to the end of the file. So we can test if the found key references a new record. If we are searching for a partial key (or using >, >=, < or <=) and the data is outside of the data file, we need to continue searching for the first key inside the data file. We do also continue searching if an index condition check function is available. */ while ((info->lastpos >= info->state->data_file_length && (search_flag != HA_READ_KEY_EXACT || last_used_keyseg != keyinfo->seg + keyinfo->keysegs)) || (info->index_cond_func && !(res= mi_check_index_cond(info, inx, buf)))) { uint not_used[2]; /* Skip rows that are inserted by other threads since we got a lock Note that this can only happen if we are not searching after an full length exact key, because the keys are sorted according to position */ if (_mi_search_next(info, keyinfo, info->lastkey, info->lastkey_length, myisam_readnext_vec[search_flag], info->s->state.key_root[inx])) break; /* Check that the found key does still match the search. _mi_search_next() delivers the next key regardless of its value. */ if (search_flag == HA_READ_KEY_EXACT && ha_key_cmp(keyinfo->seg, key_buff, info->lastkey, use_key_length, SEARCH_FIND, not_used)) { my_errno= HA_ERR_KEY_NOT_FOUND; info->lastpos= HA_OFFSET_ERROR; break; } } if (res == 2) { info->lastpos= HA_OFFSET_ERROR; if (share->concurrent_insert) rw_unlock(&share->key_root_lock[inx]); DBUG_RETURN((my_errno= HA_ERR_KEY_NOT_FOUND)); } /* Error if no row found within the data file. (Bug #29838) Do not overwrite my_errno if already at HA_OFFSET_ERROR. */ if (info->lastpos != HA_OFFSET_ERROR && info->lastpos >= info->state->data_file_length) { info->lastpos= HA_OFFSET_ERROR; my_errno= HA_ERR_KEY_NOT_FOUND; } } } if (share->concurrent_insert) rw_unlock(&share->key_root_lock[inx]); /* Calculate length of the found key; Used by mi_rnext_same */ if ((keyinfo->flag & HA_VAR_LENGTH_KEY) && last_used_keyseg && info->lastpos != HA_OFFSET_ERROR) info->last_rkey_length= _mi_keylength_part(keyinfo, info->lastkey, last_used_keyseg); else info->last_rkey_length= pack_key_length; /* Check if we don't want to have record back, only error message */ if (!buf) DBUG_RETURN(info->lastpos == HA_OFFSET_ERROR ? my_errno : 0); if (!(*info->read_record)(info,info->lastpos,buf)) { info->update|= HA_STATE_AKTIV; /* Record is read */ DBUG_RETURN(0); } info->lastpos = HA_OFFSET_ERROR; /* Didn't find key */ /* Store last used key as a base for read next */ memcpy(info->lastkey,key_buff,pack_key_length); info->last_rkey_length= pack_key_length; bzero((char*) info->lastkey+pack_key_length,info->s->base.rec_reflength); info->lastkey_length=pack_key_length+info->s->base.rec_reflength; if (search_flag == HA_READ_AFTER_KEY) info->update|=HA_STATE_NEXT_FOUND; /* Previous gives last row */ err: DBUG_RETURN(my_errno); } /* _mi_rkey */