*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.164 2004/04/01 21:28:43 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.165 2004/04/21 18:24:23 tgl Exp $
*
*
* INTERFACE ROUTINES
Buffer *userbuf,
bool keep_buf,
PgStat_Info *pgstat_info)
+{
+ /* Assume *userbuf is undefined on entry */
+ *userbuf = InvalidBuffer;
+ return heap_release_fetch(relation, snapshot, tuple,
+ userbuf, keep_buf, pgstat_info);
+}
+
+/*
+ * heap_release_fetch - retrieve tuple with given tid
+ *
+ * This has the same API as heap_fetch except that if *userbuf is not
+ * InvalidBuffer on entry, that buffer will be released before reading
+ * the new page. This saves a separate ReleaseBuffer step and hence
+ * one entry into the bufmgr when looping through multiple fetches.
+ */
+bool
+heap_release_fetch(Relation relation,
+ Snapshot snapshot,
+ HeapTuple tuple,
+ Buffer *userbuf,
+ bool keep_buf,
+ PgStat_Info *pgstat_info)
{
ItemPointer tid = &(tuple->t_self);
ItemId lp;
/*
* get the buffer from the relation descriptor. Note that this does a
- * buffer pin.
+ * buffer pin, and releases the old *userbuf if not InvalidBuffer.
*/
- buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid));
+ buffer = ReleaseAndReadBuffer(*userbuf, relation,
+ ItemPointerGetBlockNumber(tid));
if (!BufferIsValid(buffer))
elog(ERROR, "ReadBuffer(\"%s\", %lu) failed",
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.72 2003/11/29 19:51:40 pgsql Exp $
+ * $PostgreSQL: pgsql/src/backend/access/index/indexam.c,v 1.73 2004/04/21 18:24:24 tgl Exp $
*
* INTERFACE ROUTINES
* index_open - open an index relation by relation OID
SCAN_CHECKS;
GET_SCAN_PROCEDURE(rescan, amrescan);
+ /* Release any held pin on a heap page */
+ if (BufferIsValid(scan->xs_cbuf))
+ {
+ ReleaseBuffer(scan->xs_cbuf);
+ scan->xs_cbuf = InvalidBuffer;
+ }
+
scan->kill_prior_tuple = false; /* for safety */
scan->keys_are_unique = false; /* may be set by index AM */
scan->got_tuple = false;
SCAN_CHECKS;
- /* Release any previously held pin */
- if (BufferIsValid(scan->xs_cbuf))
- {
- ReleaseBuffer(scan->xs_cbuf);
- scan->xs_cbuf = InvalidBuffer;
- }
-
/*
* If we already got a tuple and it must be unique, there's no need to
* make the index AM look through any additional tuples. (This can
scan->kill_prior_tuple = false;
if (!found)
+ {
+ /* Release any held pin on a heap page */
+ if (BufferIsValid(scan->xs_cbuf))
+ {
+ ReleaseBuffer(scan->xs_cbuf);
+ scan->xs_cbuf = InvalidBuffer;
+ }
return NULL; /* failure exit */
+ }
/*
* Fetch the heap tuple and see if it matches the snapshot.
*/
- if (heap_fetch(scan->heapRelation, scan->xs_snapshot,
- heapTuple, &scan->xs_cbuf, true,
- &scan->xs_pgstat_info))
+ if (heap_release_fetch(scan->heapRelation, scan->xs_snapshot,
+ heapTuple, &scan->xs_cbuf, true,
+ &scan->xs_pgstat_info))
break;
/* Skip if no tuple at this location */
* if the tuple is dead to all transactions. If so, signal the
* index AM to not return it on future indexscans.
*
- * We told heap_fetch to keep a pin on the buffer, so we can
+ * We told heap_release_fetch to keep a pin on the buffer, so we can
* re-access the tuple here. But we must re-lock the buffer
* first. Also, it's just barely possible for an update of hint
* bits to occur here.
if (sv_infomask != heapTuple->t_data->t_infomask)
SetBufferCommitInfoNeedsSave(scan->xs_cbuf);
LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
- ReleaseBuffer(scan->xs_cbuf);
- scan->xs_cbuf = InvalidBuffer;
}
/* Success exit */
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.111 2004/01/07 18:56:24 neilc Exp $
+ * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.112 2004/04/21 18:24:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
for (;;)
{
nblkno = opaque->btpo_next;
- if (nbuf != InvalidBuffer)
- _bt_relbuf(rel, nbuf);
- nbuf = _bt_getbuf(rel, nblkno, BT_READ);
+ nbuf = _bt_relandgetbuf(rel, nbuf, nblkno, BT_READ);
page = BufferGetPage(nbuf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (!P_IGNORE(opaque))
{
BlockNumber rblkno = lpageop->btpo_next;
- if (rbuf != InvalidBuffer)
- _bt_relbuf(rel, rbuf);
- rbuf = _bt_getbuf(rel, rblkno, BT_WRITE);
+ rbuf = _bt_relandgetbuf(rel, rbuf, rblkno, BT_WRITE);
page = BufferGetPage(rbuf);
lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
if (!P_IGNORE(lpageop))
if (P_RIGHTMOST(opaque))
{
_bt_relbuf(rel, buf);
- return (InvalidBuffer);
+ return InvalidBuffer;
}
blkno = opaque->btpo_next;
start = InvalidOffsetNumber;
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.74 2003/12/21 01:23:06 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.75 2004/04/21 18:24:25 tgl Exp $
*
* NOTES
* Postgres btree pages look like ordinary relation pages. The opaque
Assert(rootblkno != P_NONE);
rootlevel = metad->btm_fastlevel;
- _bt_relbuf(rel, metabuf); /* done with the meta page */
+ /*
+ * We are done with the metapage; arrange to release it via
+ * first _bt_relandgetbuf call
+ */
+ rootbuf = metabuf;
for (;;)
{
- rootbuf = _bt_getbuf(rel, rootblkno, BT_READ);
+ rootbuf = _bt_relandgetbuf(rel, rootbuf, rootblkno, BT_READ);
rootpage = BufferGetPage(rootbuf);
rootopaque = (BTPageOpaque) PageGetSpecialPointer(rootpage);
elog(ERROR, "no live root page found in \"%s\"",
RelationGetRelationName(rel));
rootblkno = rootopaque->btpo_next;
-
- _bt_relbuf(rel, rootbuf);
}
/* Note: can't check btpo.level on deleted pages */
rootblkno = metad->btm_root;
rootlevel = metad->btm_level;
- _bt_relbuf(rel, metabuf); /* done with the meta page */
+ /*
+ * We are done with the metapage; arrange to release it via
+ * first _bt_relandgetbuf call
+ */
+ rootbuf = metabuf;
for (;;)
{
- rootbuf = _bt_getbuf(rel, rootblkno, BT_READ);
+ rootbuf = _bt_relandgetbuf(rel, rootbuf, rootblkno, BT_READ);
rootpage = BufferGetPage(rootbuf);
rootopaque = (BTPageOpaque) PageGetSpecialPointer(rootpage);
elog(ERROR, "no live root page found in \"%s\"",
RelationGetRelationName(rel));
rootblkno = rootopaque->btpo_next;
-
- _bt_relbuf(rel, rootbuf);
}
/* Note: can't check btpo.level on deleted pages */
return buf;
}
+/*
+ * _bt_relandgetbuf() -- release a locked buffer and get another one.
+ *
+ * This is equivalent to _bt_relbuf followed by _bt_getbuf, with the
+ * exception that blkno may not be P_NEW. Also, if obuf is InvalidBuffer
+ * then it reduces to just _bt_getbuf; allowing this case simplifies some
+ * callers. The motivation for using this is to avoid two entries to the
+ * bufmgr when one will do.
+ */
+Buffer
+_bt_relandgetbuf(Relation rel, Buffer obuf, BlockNumber blkno, int access)
+{
+ Buffer buf;
+
+ Assert(blkno != P_NEW);
+ if (BufferIsValid(obuf))
+ LockBuffer(obuf, BUFFER_LOCK_UNLOCK);
+ buf = ReleaseAndReadBuffer(obuf, rel, blkno);
+ LockBuffer(buf, access);
+ return buf;
+}
+
/*
* _bt_relbuf() -- release a locked buffer.
*
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.113 2004/02/10 03:42:43 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtree.c,v 1.114 2004/04/21 18:24:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
for (;;)
{
blkno = opaque->btpo_next;
- if (nextbuf != InvalidBuffer)
- _bt_relbuf(rel, nextbuf);
- nextbuf = _bt_getbuf(rel, blkno, BT_READ);
+ nextbuf = _bt_relandgetbuf(rel, nextbuf, blkno, BT_READ);
page = BufferGetPage(nextbuf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (!P_IGNORE(opaque))
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.86 2003/12/21 17:52:34 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtsearch.c,v 1.87 2004/04/21 18:24:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
new_stack->bts_parent = stack_in;
/* drop the read lock on the parent page, acquire one on the child */
- _bt_relbuf(rel, *bufP);
- *bufP = _bt_getbuf(rel, blkno, BT_READ);
+ *bufP = _bt_relandgetbuf(rel, *bufP, blkno, BT_READ);
/* okay, all set to move down a level */
stack_in = new_stack;
/* step right one page */
BlockNumber rblkno = opaque->btpo_next;
- _bt_relbuf(rel, buf);
- buf = _bt_getbuf(rel, rblkno, access);
+ buf = _bt_relandgetbuf(rel, buf, rblkno, access);
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
}
}
/* step right one page */
blkno = opaque->btpo_next;
- _bt_relbuf(rel, *bufP);
- *bufP = _bt_getbuf(rel, blkno, BT_READ);
+ *bufP = _bt_relandgetbuf(rel, *bufP, blkno, BT_READ);
page = BufferGetPage(*bufP);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (!P_IGNORE(opaque))
obknum = BufferGetBlockNumber(buf);
/* step left */
blkno = lblkno = opaque->btpo_prev;
- _bt_relbuf(rel, buf);
- buf = _bt_getbuf(rel, blkno, BT_READ);
+ buf = _bt_relandgetbuf(rel, buf, blkno, BT_READ);
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (P_RIGHTMOST(opaque) || ++tries > 4)
break;
blkno = opaque->btpo_next;
- _bt_relbuf(rel, buf);
- buf = _bt_getbuf(rel, blkno, BT_READ);
+ buf = _bt_relandgetbuf(rel, buf, blkno, BT_READ);
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
}
/* Return to the original page to see what's up */
- _bt_relbuf(rel, buf);
- buf = _bt_getbuf(rel, obknum, BT_READ);
+ buf = _bt_relandgetbuf(rel, buf, obknum, BT_READ);
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (P_ISDELETED(opaque))
elog(ERROR, "fell off the end of \"%s\"",
RelationGetRelationName(rel));
blkno = opaque->btpo_next;
- _bt_relbuf(rel, buf);
- buf = _bt_getbuf(rel, blkno, BT_READ);
+ buf = _bt_relandgetbuf(rel, buf, blkno, BT_READ);
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (!P_ISDELETED(opaque))
if (blkno == P_NONE)
elog(ERROR, "fell off the end of \"%s\"",
RelationGetRelationName(rel));
- _bt_relbuf(rel, buf);
- buf = _bt_getbuf(rel, blkno, BT_READ);
+ buf = _bt_relandgetbuf(rel, buf, blkno, BT_READ);
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
}
itup = &(btitem->bti_itup);
blkno = ItemPointerGetBlockNumber(&(itup->t_tid));
- _bt_relbuf(rel, buf);
- buf = _bt_getbuf(rel, blkno, BT_READ);
+ buf = _bt_relandgetbuf(rel, buf, blkno, BT_READ);
page = BufferGetPage(buf);
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
}
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/executor/nodeIndexscan.c,v 1.92 2004/02/28 19:46:05 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/executor/nodeIndexscan.c,v 1.93 2004/04/21 18:24:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
slot = node->ss.ss_ScanTupleSlot;
scanrelid = ((IndexScan *) node->ss.ps.plan)->scan.scanrelid;
+ /*
+ * Clear any reference to the previously returned tuple. The idea here
+ * is to not have the tuple slot be the last holder of a pin on that
+ * tuple's buffer; if it is, we'll need a separate visit to the bufmgr
+ * to release the buffer. By clearing here, we get to have the release
+ * done by ReleaseAndReadBuffer inside index_getnext.
+ */
+ ExecClearTuple(slot);
+
/*
* Check if we are evaluating PlanQual for tuple of this relation.
* Additional checking is not good, but no other way for now. We could
{
List *qual;
- ExecClearTuple(slot);
if (estate->es_evTupleNull[scanrelid - 1])
return slot; /* return empty slot */
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/executor/nodeSeqscan.c,v 1.47 2003/11/29 19:51:48 pgsql Exp $
+ * $PostgreSQL: pgsql/src/backend/executor/nodeSeqscan.c,v 1.48 2004/04/21 18:24:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
direction = estate->es_direction;
slot = node->ss_ScanTupleSlot;
+ /*
+ * Clear any reference to the previously returned tuple. The idea here
+ * is to not have the tuple slot be the last holder of a pin on that
+ * tuple's buffer; if it is, we'll need a separate visit to the bufmgr
+ * to release the buffer. By clearing here, we get to have the release
+ * done by ReleaseAndReadBuffer inside heap_getnext.
+ */
+ ExecClearTuple(slot);
+
/*
* Check if we are evaluating PlanQual for tuple of this relation.
* Additional checking is not good, but no other way for now. We could
if (estate->es_evTuple != NULL &&
estate->es_evTuple[scanrelid - 1] != NULL)
{
- ExecClearTuple(slot);
if (estate->es_evTupleNull[scanrelid - 1])
return slot; /* return empty slot */
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/executor/nodeTidscan.c,v 1.36 2003/11/29 19:51:48 pgsql Exp $
+ * $PostgreSQL: pgsql/src/backend/executor/nodeTidscan.c,v 1.37 2004/04/21 18:24:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
slot = node->ss.ss_ScanTupleSlot;
scanrelid = ((TidScan *) node->ss.ps.plan)->scan.scanrelid;
+ /*
+ * Clear any reference to the previously returned tuple. This doesn't
+ * offer any great performance benefit, but it keeps this code in sync
+ * with SeqNext and IndexNext.
+ */
+ ExecClearTuple(slot);
+
/*
* Check if we are evaluating PlanQual for tuple of this relation.
* Additional checking is not good, but no other way for now. We could
if (estate->es_evTuple != NULL &&
estate->es_evTuple[scanrelid - 1] != NULL)
{
- ExecClearTuple(slot);
if (estate->es_evTupleNull[scanrelid - 1])
return slot; /* return empty slot */
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/access/heapam.h,v 1.88 2004/04/01 21:28:45 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/access/heapam.h,v 1.89 2004/04/21 18:24:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
extern bool heap_fetch(Relation relation, Snapshot snapshot,
HeapTuple tuple, Buffer *userbuf, bool keep_buf,
PgStat_Info *pgstat_info);
+extern bool heap_release_fetch(Relation relation, Snapshot snapshot,
+ HeapTuple tuple, Buffer *userbuf, bool keep_buf,
+ PgStat_Info *pgstat_info);
extern ItemPointer heap_get_latest_tid(Relation relation, Snapshot snapshot,
ItemPointer tid);
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/access/nbtree.h,v 1.76 2004/02/03 17:34:03 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/access/nbtree.h,v 1.77 2004/04/21 18:24:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
extern Buffer _bt_getroot(Relation rel, int access);
extern Buffer _bt_gettrueroot(Relation rel);
extern Buffer _bt_getbuf(Relation rel, BlockNumber blkno, int access);
+extern Buffer _bt_relandgetbuf(Relation rel, Buffer obuf,
+ BlockNumber blkno, int access);
extern void _bt_relbuf(Relation rel, Buffer buf);
extern void _bt_wrtbuf(Relation rel, Buffer buf);
extern void _bt_wrtnorelbuf(Relation rel, Buffer buf);
projects / postgresql / commitdiff