From ece01aae479227d9836294b287d872c5a6146a11 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 7 Jun 2012 17:42:27 -0400
Subject: Scan the buffer pool just once, not once per fork, during relation
 drop.

This provides a speedup of about 4X when NBuffers is large enough.
There is also a useful reduction in sinval traffic, since we
only do CacheInvalidateSmgr() once not once per fork.

Simon Riggs, reviewed and somewhat revised by Tom Lane
---
 src/backend/storage/buffer/bufmgr.c | 42 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

(limited to 'src/backend/storage/buffer/bufmgr.c')

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index b178eee2214..d46faaf958d 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -2020,7 +2020,7 @@ BufferIsPermanent(Buffer buffer)
  *		DropRelFileNodeBuffers
  *
  *		This function removes from the buffer pool all the pages of the
- *		specified relation that have block numbers >= firstDelBlock.
+ *		specified relation fork that have block numbers >= firstDelBlock.
  *		(In particular, with firstDelBlock = 0, all pages are removed.)
  *		Dirty pages are simply dropped, without bothering to write them
  *		out first.	Therefore, this is NOT rollback-able, and so should be
@@ -2089,6 +2089,46 @@ DropRelFileNodeBuffers(RelFileNodeBackend rnode, ForkNumber forkNum,
 	}
 }
 
+/* ---------------------------------------------------------------------
+ *		DropRelFileNodeAllBuffers
+ *
+ *		This function removes from the buffer pool all the pages of all
+ *		forks of the specified relation.  It's equivalent to calling
+ *		DropRelFileNodeBuffers once per fork with firstDelBlock = 0.
+ * --------------------------------------------------------------------
+ */
+void
+DropRelFileNodeAllBuffers(RelFileNodeBackend rnode)
+{
+	int			i;
+
+	/* If it's a local relation, it's localbuf.c's problem. */
+	if (rnode.backend != InvalidBackendId)
+	{
+		if (rnode.backend == MyBackendId)
+			DropRelFileNodeAllLocalBuffers(rnode.node);
+		return;
+	}
+
+	for (i = 0; i < NBuffers; i++)
+	{
+		volatile BufferDesc *bufHdr = &BufferDescriptors[i];
+
+		/*
+		 * As in DropRelFileNodeBuffers, an unlocked precheck should be safe
+		 * and saves some cycles.
+		 */
+		if (!RelFileNodeEquals(bufHdr->tag.rnode, rnode.node))
+			continue;
+
+		LockBufHdr(bufHdr);
+		if (RelFileNodeEquals(bufHdr->tag.rnode, rnode.node))
+			InvalidateBuffer(bufHdr);	/* releases spinlock */
+		else
+			UnlockBufHdr(bufHdr);
+	}
+}
+
 /* ---------------------------------------------------------------------
  *		DropDatabaseBuffers
  *
-- 
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