1 /* Copyright (c) 2000, 2001, 2004-2007 MySQL AB
3 This program is free software; you can redistribute it and/or modify
4 it under the terms of the GNU General Public License as published by
5 the Free Software Foundation; version 2 of the License.
7 This program is distributed in the hope that it will be useful,
8 but WITHOUT ANY WARRANTY; without even the implied warranty of
9 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 GNU General Public License for more details.
12 You should have received a copy of the GNU General Public License
13 along with this program; if not, write to the Free Software
14 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */
16 #include "myisamdef.h"
19 Read previous row with the same key as previous read
20 One may have done a write, update or delete of the previous row.
21 NOTE! Even if one changes the previous row, the next read is done
22 based on the position of the last used key!
25 int mi_rprev(MI_INFO
*info
, uchar
*buf
, int inx
)
29 MYISAM_SHARE
*share
=info
->s
;
30 DBUG_ENTER("mi_rprev");
32 if ((inx
= _mi_check_index(info
,inx
)) < 0)
33 DBUG_RETURN(my_errno
);
34 flag
=SEARCH_SMALLER
; /* Read previous */
35 if (info
->lastpos
== HA_OFFSET_ERROR
&& info
->update
& HA_STATE_NEXT_FOUND
)
36 flag
=0; /* Read last */
38 if (fast_mi_readinfo(info
))
39 DBUG_RETURN(my_errno
);
40 changed
=_mi_test_if_changed(info
);
41 if (share
->concurrent_insert
)
42 rw_rdlock(&share
->key_root_lock
[inx
]);
44 error
=_mi_search_last(info
, share
->keyinfo
+inx
,
45 share
->state
.key_root
[inx
]);
47 error
=_mi_search_next(info
,share
->keyinfo
+inx
,info
->lastkey
,
48 info
->lastkey_length
,flag
,
49 share
->state
.key_root
[inx
]);
51 error
=_mi_search(info
,share
->keyinfo
+inx
,info
->lastkey
,
52 USE_WHOLE_KEY
, flag
, share
->state
.key_root
[inx
]);
54 if (share
->concurrent_insert
)
58 while (info
->lastpos
>= info
->state
->data_file_length
)
60 /* Skip rows that are inserted by other threads since we got a lock */
61 if ((error
=_mi_search_next(info
,share
->keyinfo
+inx
,info
->lastkey
,
64 share
->state
.key_root
[inx
])))
68 rw_unlock(&share
->key_root_lock
[inx
]);
70 info
->update
&= (HA_STATE_CHANGED
| HA_STATE_ROW_CHANGED
);
71 info
->update
|= HA_STATE_PREV_FOUND
;
74 if (my_errno
== HA_ERR_KEY_NOT_FOUND
)
75 my_errno
=HA_ERR_END_OF_FILE
;
79 DBUG_RETURN(info
->lastpos
==HA_OFFSET_ERROR
? my_errno
: 0);
81 else if (!(*info
->read_record
)(info
,info
->lastpos
,buf
))
83 info
->update
|= HA_STATE_AKTIV
; /* Record is read */
86 DBUG_RETURN(my_errno
);