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, 58 insertions, 29 deletions

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 3b6938135ac..4c09df1ba78 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.256 2010/02/26 02:00:59 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.257 2010/08/13 20:10:52 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -95,7 +95,8 @@ static void WaitIO(volatile BufferDesc *buf);
 static bool StartBufferIO(volatile BufferDesc *buf, bool forInput);
 static void TerminateBufferIO(volatile BufferDesc *buf, bool clear_dirty,
 				  int set_flag_bits);
-static void buffer_write_error_callback(void *arg);
+static void shared_buffer_write_error_callback(void *arg);
+static void local_buffer_write_error_callback(void *arg);
 static volatile BufferDesc *BufferAlloc(SMgrRelation smgr, ForkNumber forkNum,
 			BlockNumber blockNum,
 			BufferAccessStrategy strategy,
@@ -141,7 +142,8 @@ PrefetchBuffer(Relation reln, ForkNumber forkNum, BlockNumber blockNum)
 		int			buf_id;
 
 		/* create a tag so we can lookup the buffer */
-		INIT_BUFFERTAG(newTag, reln->rd_smgr->smgr_rnode, forkNum, blockNum);
+		INIT_BUFFERTAG(newTag, reln->rd_smgr->smgr_rnode.node,
+					   forkNum, blockNum);
 
 		/* determine its hash code and partition lock ID */
 		newHash = BufTableHashCode(&newTag);
@@ -251,18 +253,21 @@ ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum,
  * ReadBufferWithoutRelcache -- like ReadBufferExtended, but doesn't require
  *		a relcache entry for the relation.
  *
- * NB: caller is assumed to know what it's doing if isTemp is true.
+ * NB: At present, this function may not be used on temporary relations, which
+ * is OK, because we only use it during XLOG replay.  If in the future we
+ * want to use it on temporary relations, we could pass the backend ID as an
+ * additional parameter.
  */
 Buffer
-ReadBufferWithoutRelcache(RelFileNode rnode, bool isTemp,
-						  ForkNumber forkNum, BlockNumber blockNum,
-						  ReadBufferMode mode, BufferAccessStrategy strategy)
+ReadBufferWithoutRelcache(RelFileNode rnode, ForkNumber forkNum,
+						  BlockNumber blockNum, ReadBufferMode mode,
+						  BufferAccessStrategy strategy)
 {
 	bool		hit;
 
-	SMgrRelation smgr = smgropen(rnode);
+	SMgrRelation smgr = smgropen(rnode, InvalidBackendId);
 
-	return ReadBuffer_common(smgr, isTemp, forkNum, blockNum, mode, strategy,
+	return ReadBuffer_common(smgr, false, forkNum, blockNum, mode, strategy,
 							 &hit);
 }
 
@@ -414,7 +419,7 @@ ReadBuffer_common(SMgrRelation smgr, bool isLocalBuf, ForkNumber forkNum,
 	{
 		/* new buffers are zero-filled */
 		MemSet((char *) bufBlock, 0, BLCKSZ);
-		smgrextend(smgr, forkNum, blockNum, (char *) bufBlock, isLocalBuf);
+		smgrextend(smgr, forkNum, blockNum, (char *) bufBlock, false);
 	}
 	else
 	{
@@ -465,10 +470,10 @@ ReadBuffer_common(SMgrRelation smgr, bool isLocalBuf, ForkNumber forkNum,
 		VacuumCostBalance += VacuumCostPageMiss;
 
 	TRACE_POSTGRESQL_BUFFER_READ_DONE(forkNum, blockNum,
-									  smgr->smgr_rnode.spcNode,
-									  smgr->smgr_rnode.dbNode,
-									  smgr->smgr_rnode.relNode,
-									  isLocalBuf,
+									  smgr->smgr_rnode.node.spcNode,
+									  smgr->smgr_rnode.node.dbNode,
+									  smgr->smgr_rnode.node.relNode,
+									  smgr->smgr_rnode.backend,
 									  isExtend,
 									  found);
 
@@ -512,7 +517,7 @@ BufferAlloc(SMgrRelation smgr, ForkNumber forkNum,
 	bool		valid;
 
 	/* create a tag so we can lookup the buffer */
-	INIT_BUFFERTAG(newTag, smgr->smgr_rnode, forkNum, blockNum);
+	INIT_BUFFERTAG(newTag, smgr->smgr_rnode.node, forkNum, blockNum);
 
 	/* determine its hash code and partition lock ID */
 	newHash = BufTableHashCode(&newTag);
@@ -1693,21 +1698,24 @@ PrintBufferLeakWarning(Buffer buffer)
 	volatile BufferDesc *buf;
 	int32		loccount;
 	char	   *path;
+	BackendId	backend;
 
 	Assert(BufferIsValid(buffer));
 	if (BufferIsLocal(buffer))
 	{
 		buf = &LocalBufferDescriptors[-buffer - 1];
 		loccount = LocalRefCount[-buffer - 1];
+		backend = MyBackendId;
 	}
 	else
 	{
 		buf = &BufferDescriptors[buffer - 1];
 		loccount = PrivateRefCount[buffer - 1];
+		backend = InvalidBackendId;
 	}
 
 	/* theoretically we should lock the bufhdr here */
-	path = relpath(buf->tag.rnode, buf->tag.forkNum);
+	path = relpathbackend(buf->tag.rnode, backend, buf->tag.forkNum);
 	elog(WARNING,
 		 "buffer refcount leak: [%03d] "
 		 "(rel=%s, blockNum=%u, flags=0x%x, refcount=%u %d)",
@@ -1831,14 +1839,14 @@ FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln)
 		return;
 
 	/* Setup error traceback support for ereport() */
-	errcontext.callback = buffer_write_error_callback;
+	errcontext.callback = shared_buffer_write_error_callback;
 	errcontext.arg = (void *) buf;
 	errcontext.previous = error_context_stack;
 	error_context_stack = &errcontext;
 
 	/* Find smgr relation for buffer */
 	if (reln == NULL)
-		reln = smgropen(buf->tag.rnode);
+		reln = smgropen(buf->tag.rnode, InvalidBackendId);
 
 	TRACE_POSTGRESQL_BUFFER_FLUSH_START(buf->tag.forkNum,
 										buf->tag.blockNum,
@@ -1929,14 +1937,15 @@ RelationGetNumberOfBlocks(Relation relation)
  * --------------------------------------------------------------------
  */
 void
-DropRelFileNodeBuffers(RelFileNode rnode, ForkNumber forkNum, bool istemp,
+DropRelFileNodeBuffers(RelFileNodeBackend rnode, ForkNumber forkNum,
 					   BlockNumber firstDelBlock)
 {
 	int			i;
 
-	if (istemp)
+	if (rnode.backend != InvalidBackendId)
 	{
-		DropRelFileNodeLocalBuffers(rnode, forkNum, firstDelBlock);
+		if (rnode.backend == MyBackendId)
+			DropRelFileNodeLocalBuffers(rnode.node, forkNum, firstDelBlock);
 		return;
 	}
 
@@ -1945,7 +1954,7 @@ DropRelFileNodeBuffers(RelFileNode rnode, ForkNumber forkNum, bool istemp,
 		volatile BufferDesc *bufHdr = &BufferDescriptors[i];
 
 		LockBufHdr(bufHdr);
-		if (RelFileNodeEquals(bufHdr->tag.rnode, rnode) &&
+		if (RelFileNodeEquals(bufHdr->tag.rnode, rnode.node) &&
 			bufHdr->tag.forkNum == forkNum &&
 			bufHdr->tag.blockNum >= firstDelBlock)
 			InvalidateBuffer(bufHdr);	/* releases spinlock */
@@ -2008,7 +2017,7 @@ PrintBufferDescs(void)
 			 "[%02d] (freeNext=%d, rel=%s, "
 			 "blockNum=%u, flags=0x%x, refcount=%u %d)",
 			 i, buf->freeNext,
-			 relpath(buf->tag.rnode, buf->tag.forkNum),
+			 relpathbackend(buf->tag.rnode, InvalidBackendId, buf->tag.forkNum),
 			 buf->tag.blockNum, buf->flags,
 			 buf->refcount, PrivateRefCount[i]);
 	}
@@ -2078,7 +2087,7 @@ FlushRelationBuffers(Relation rel)
 				ErrorContextCallback errcontext;
 
 				/* Setup error traceback support for ereport() */
-				errcontext.callback = buffer_write_error_callback;
+				errcontext.callback = local_buffer_write_error_callback;
 				errcontext.arg = (void *) bufHdr;
 				errcontext.previous = error_context_stack;
 				error_context_stack = &errcontext;
@@ -2087,7 +2096,7 @@ FlushRelationBuffers(Relation rel)
 						  bufHdr->tag.forkNum,
 						  bufHdr->tag.blockNum,
 						  (char *) LocalBufHdrGetBlock(bufHdr),
-						  true);
+						  false);
 
 				bufHdr->flags &= ~(BM_DIRTY | BM_JUST_DIRTIED);
 
@@ -2699,8 +2708,9 @@ AbortBufferIO(void)
 			if (sv_flags & BM_IO_ERROR)
 			{
 				/* Buffer is pinned, so we can read tag without spinlock */
-				char	   *path = relpath(buf->tag.rnode, buf->tag.forkNum);
+				char	   *path;
 
+				path = relpathperm(buf->tag.rnode, buf->tag.forkNum);
 				ereport(WARNING,
 						(errcode(ERRCODE_IO_ERROR),
 						 errmsg("could not write block %u of %s",
@@ -2714,17 +2724,36 @@ AbortBufferIO(void)
 }
 
 /*
- * Error context callback for errors occurring during buffer writes.
+ * Error context callback for errors occurring during shared buffer writes.
  */
 static void
-buffer_write_error_callback(void *arg)
+shared_buffer_write_error_callback(void *arg)
 {
 	volatile BufferDesc *bufHdr = (volatile BufferDesc *) arg;
 
 	/* Buffer is pinned, so we can read the tag without locking the spinlock */
 	if (bufHdr != NULL)
 	{
-		char	   *path = relpath(bufHdr->tag.rnode, bufHdr->tag.forkNum);
+		char	   *path = relpathperm(bufHdr->tag.rnode, bufHdr->tag.forkNum);
+
+		errcontext("writing block %u of relation %s",
+				   bufHdr->tag.blockNum, path);
+		pfree(path);
+	}
+}
+
+/*
+ * Error context callback for errors occurring during local buffer writes.
+ */
+static void
+local_buffer_write_error_callback(void *arg)
+{
+	volatile BufferDesc *bufHdr = (volatile BufferDesc *) arg;
+
+	if (bufHdr != NULL)
+	{
+		char	   *path = relpathbackend(bufHdr->tag.rnode, MyBackendId,
+										 bufHdr->tag.forkNum);
 
 		errcontext("writing block %u of relation %s",
 				   bufHdr->tag.blockNum, path);