diff options
Diffstat (limited to 'storage/heap/hp_rnext.c')
| -rw-r--r-- | storage/heap/hp_rnext.c | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/storage/heap/hp_rnext.c b/storage/heap/hp_rnext.c new file mode 100644 index 00000000..f227ce4d --- /dev/null +++ b/storage/heap/hp_rnext.c @@ -0,0 +1,130 @@ +/* Copyright (c) 2000, 2002, 2005-2007 MySQL AB + Use is subject to license terms + + 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */ + +#include "heapdef.h" + +/* Read next record with the same key */ + +int heap_rnext(HP_INFO *info, uchar *record) +{ + uchar *pos; + HP_SHARE *share=info->s; + HP_KEYDEF *keyinfo; + DBUG_ENTER("heap_rnext"); + + if (info->lastinx < 0) + DBUG_RETURN(my_errno=HA_ERR_WRONG_INDEX); + + keyinfo = share->keydef + info->lastinx; + if (keyinfo->algorithm == HA_KEY_ALG_BTREE) + { + heap_rb_param custom_arg; + + /* If no active record and last was not deleted */ + if (!(info->update & (HA_STATE_AKTIV | HA_STATE_NO_KEY | + HA_STATE_DELETED))) + { + if (info->update & HA_STATE_NEXT_FOUND) + pos= 0; /* Can't search after last row */ + else + { + /* Last was 'prev' before first record; search after first record */ + pos= tree_search_edge(&keyinfo->rb_tree, info->parents, + &info->last_pos, offsetof(TREE_ELEMENT, left)); + } + } + else if (info->last_pos) + { + /* + We enter this branch for non-DELETE queries after heap_rkey() + or heap_rfirst(). As last key position (info->last_pos) is available, + we only need to climb the tree using tree_search_next(). + */ + pos = tree_search_next(&keyinfo->rb_tree, &info->last_pos, + offsetof(TREE_ELEMENT, left), + offsetof(TREE_ELEMENT, right)); + } + else if (!info->lastkey_len) + { + /* + We enter this branch only for DELETE queries after heap_rfirst(). E.g. + DELETE FROM t1 WHERE a<10. As last key position is not available + (last key is removed by heap_delete()), we must restart search as it + is done in heap_rfirst(). + + It should be safe to handle this situation without this branch. That is + branch below should find smallest element in a tree as lastkey_len is + zero. tree_search_edge() is a kind of optimisation here as it should be + faster than tree_search_key(). + */ + pos= tree_search_edge(&keyinfo->rb_tree, info->parents, + &info->last_pos, offsetof(TREE_ELEMENT, left)); + } + else + { + /* + We enter this branch only for DELETE queries after heap_rkey(). E.g. + DELETE FROM t1 WHERE a=10. As last key position is not available + (last key is removed by heap_delete()), we must restart search as it + is done in heap_rkey(). + */ + custom_arg.keyseg = keyinfo->seg; + custom_arg.key_length = info->lastkey_len; + custom_arg.search_flag = SEARCH_SAME | SEARCH_FIND; + info->last_find_flag= HA_READ_KEY_OR_NEXT; + pos = tree_search_key(&keyinfo->rb_tree, info->lastkey, info->parents, + &info->last_pos, info->last_find_flag, &custom_arg); + } + if (pos) + { + memcpy(&pos, pos + (*keyinfo->get_key_length)(keyinfo, pos), + sizeof(uchar*)); + info->current_ptr = pos; + } + else + { + my_errno = HA_ERR_KEY_NOT_FOUND; + } + } + else + { + if (info->current_hash_ptr) + pos= hp_search_next(info, keyinfo, info->lastkey, + info->current_hash_ptr); + else + { + if (!info->current_ptr && (info->update & HA_STATE_NEXT_FOUND)) + { + pos=0; /* Read next after last */ + my_errno=HA_ERR_KEY_NOT_FOUND; + } + else if (!info->current_ptr) /* Deleted or first call */ + pos= hp_search(info, keyinfo, info->lastkey, 0); + else + pos= hp_search(info, keyinfo, info->lastkey, 1); + } + } + if (!pos) + { + info->update=HA_STATE_NEXT_FOUND; /* For heap_rprev */ + if (my_errno == HA_ERR_KEY_NOT_FOUND) + my_errno=HA_ERR_END_OF_FILE; + DBUG_RETURN(my_errno); + } + memcpy(record,pos,(size_t) share->reclength); + info->update=HA_STATE_AKTIV | HA_STATE_NEXT_FOUND; + DBUG_RETURN(0); +} |