Include the backend ID in the relpath of temporary relations.

This allows us to reliably remove all leftover temporary relation
files on cluster startup without reference to system catalogs or WAL;
therefore, we no longer include temporary relations in XLOG_XACT_COMMIT
and XLOG_XACT_ABORT WAL records.

Since these changes require including a backend ID in each
SharedInvalSmgrMsg, the size of the SharedInvalidationMessage.id
field has been reduced from two bytes to one, and the maximum number
of connections has been reduced from INT_MAX / 4 to 2^23-1.  It would
be possible to remove these restrictions by increasing the size of
SharedInvalidationMessage by 4 bytes, but right now that doesn't seem
like a good trade-off.

Review by Jaime Casanova and Tom Lane.

1 files changed, 10 insertions, 8 deletions

diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c
index 2b783f87f45..dd067737c99 100644
--- a/src/backend/storage/buffer/localbuf.c
+++ b/src/backend/storage/buffer/localbuf.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/buffer/localbuf.c,v 1.89 2010/01/02 16:57:51 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/buffer/localbuf.c,v 1.90 2010/08/13 20:10:52 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -68,7 +68,7 @@ LocalPrefetchBuffer(SMgrRelation smgr, ForkNumber forkNum,
 	BufferTag	newTag;			/* identity of requested block */
 	LocalBufferLookupEnt *hresult;
 
-	INIT_BUFFERTAG(newTag, smgr->smgr_rnode, forkNum, blockNum);
+	INIT_BUFFERTAG(newTag, smgr->smgr_rnode.node, forkNum, blockNum);
 
 	/* Initialize local buffers if first request in this session */
 	if (LocalBufHash == NULL)
@@ -110,7 +110,7 @@ LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
 	int			trycounter;
 	bool		found;
 
-	INIT_BUFFERTAG(newTag, smgr->smgr_rnode, forkNum, blockNum);
+	INIT_BUFFERTAG(newTag, smgr->smgr_rnode.node, forkNum, blockNum);
 
 	/* Initialize local buffers if first request in this session */
 	if (LocalBufHash == NULL)
@@ -127,7 +127,7 @@ LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
 		Assert(BUFFERTAGS_EQUAL(bufHdr->tag, newTag));
 #ifdef LBDEBUG
 		fprintf(stderr, "LB ALLOC (%u,%d,%d) %d\n",
-				smgr->smgr_rnode.relNode, forkNum, blockNum, -b - 1);
+				smgr->smgr_rnode.node.relNode, forkNum, blockNum, -b - 1);
 #endif
 		/* this part is equivalent to PinBuffer for a shared buffer */
 		if (LocalRefCount[b] == 0)
@@ -150,7 +150,8 @@ LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
 
 #ifdef LBDEBUG
 	fprintf(stderr, "LB ALLOC (%u,%d,%d) %d\n",
-		 smgr->smgr_rnode.relNode, forkNum, blockNum, -nextFreeLocalBuf - 1);
+		 smgr->smgr_rnode.node.relNode, forkNum, blockNum,
+		 -nextFreeLocalBuf - 1);
 #endif
 
 	/*
@@ -198,14 +199,14 @@ LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
 		SMgrRelation oreln;
 
 		/* Find smgr relation for buffer */
-		oreln = smgropen(bufHdr->tag.rnode);
+		oreln = smgropen(bufHdr->tag.rnode, MyBackendId);
 
 		/* And write... */
 		smgrwrite(oreln,
 				  bufHdr->tag.forkNum,
 				  bufHdr->tag.blockNum,
 				  (char *) LocalBufHdrGetBlock(bufHdr),
-				  true);
+				  false);
 
 		/* Mark not-dirty now in case we error out below */
 		bufHdr->flags &= ~BM_DIRTY;
@@ -309,7 +310,8 @@ DropRelFileNodeLocalBuffers(RelFileNode rnode, ForkNumber forkNum,
 			if (LocalRefCount[i] != 0)
 				elog(ERROR, "block %u of %s is still referenced (local %u)",
 					 bufHdr->tag.blockNum,
-					 relpath(bufHdr->tag.rnode, bufHdr->tag.forkNum),
+					 relpathbackend(bufHdr->tag.rnode, MyBackendId,
+								   bufHdr->tag.forkNum),
 					 LocalRefCount[i]);
 			/* Remove entry from hashtable */
 			hresult = (LocalBufferLookupEnt *)