From: Neil Conway <neilc@samurai.com>
Date: Wed, 17 Nov 2004 03:13:38 +0000 (+0000)
Subject: Micro-optimization of markpos() and restrpos() in btree and hash indexes.
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=770704cb985cf38a8a0aa61d22f67e4f5ce51cbb;p=users%2Fbernd%2Fpostgres.git

Micro-optimization of markpos() and restrpos() in btree and hash indexes.
Rather than using ReadBuffer() to increment the reference count on an
already-pinned buffer, we should use IncrBufferRefCount() as it is
faster and does not require acquiring the BufMgrLock.
---

diff --git a/src/backend/access/hash/hash.c b/src/backend/access/hash/hash.c
index de4058a0f6..56233426ea 100644
--- a/src/backend/access/hash/hash.c
+++ b/src/backend/access/hash/hash.c
@@ -397,9 +397,8 @@ hashmarkpos(PG_FUNCTION_ARGS)
 	/* bump pin count on currentItemData and copy to currentMarkData */
 	if (ItemPointerIsValid(&(scan->currentItemData)))
 	{
-		so->hashso_mrkbuf = _hash_getbuf(rel,
-								 BufferGetBlockNumber(so->hashso_curbuf),
-										 HASH_NOLOCK);
+		IncrBufferRefCount(so->hashso_curbuf);
+		so->hashso_mrkbuf = so->hashso_curbuf;
 		scan->currentMarkData = scan->currentItemData;
 	}
 
@@ -425,9 +424,8 @@ hashrestrpos(PG_FUNCTION_ARGS)
 	/* bump pin count on currentMarkData and copy to currentItemData */
 	if (ItemPointerIsValid(&(scan->currentMarkData)))
 	{
-		so->hashso_curbuf = _hash_getbuf(rel,
-								 BufferGetBlockNumber(so->hashso_mrkbuf),
-										 HASH_NOLOCK);
+		IncrBufferRefCount(so->hashso_mrkbuf);
+		so->hashso_curbuf = so->hashso_mrkbuf;
 		scan->currentItemData = scan->currentMarkData;
 	}
 
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index bbf6d6c949..43475359a5 100644
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -477,8 +477,8 @@ btmarkpos(PG_FUNCTION_ARGS)
 	/* bump pin on current buffer for assignment to mark buffer */
 	if (ItemPointerIsValid(&(scan->currentItemData)))
 	{
-		so->btso_mrkbuf = ReadBuffer(scan->indexRelation,
-								  BufferGetBlockNumber(so->btso_curbuf));
+		IncrBufferRefCount(so->btso_curbuf);
+		so->btso_mrkbuf = so->btso_curbuf;
 		scan->currentMarkData = scan->currentItemData;
 		so->mrkHeapIptr = so->curHeapIptr;
 	}
@@ -509,8 +509,8 @@ btrestrpos(PG_FUNCTION_ARGS)
 	/* bump pin on marked buffer */
 	if (ItemPointerIsValid(&(scan->currentMarkData)))
 	{
-		so->btso_curbuf = ReadBuffer(scan->indexRelation,
-								  BufferGetBlockNumber(so->btso_mrkbuf));
+		IncrBufferRefCount(so->btso_mrkbuf);
+		so->btso_curbuf = so->btso_mrkbuf;
 		scan->currentItemData = scan->currentMarkData;
 		so->curHeapIptr = so->mrkHeapIptr;
 	}