Properly set relpersistence for fake relcache entries.

robertmhaas · robertmhaas · commit beb850e1d873 · 2012-09-14T09:35:07.000-04:00
This can result in buffers failing to be properly flushed at
checkpoint time, leading to data loss.

Report, diagnosis, and patch by Jeff Davis.
diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
@@ -394,6 +394,8 @@ CreateFakeRelcacheEntry(RelFileNode rnode)
 	FakeRelCacheEntry fakeentry;
 	Relation	rel;
 
+	Assert(InRecovery);
+
 	/* Allocate the Relation struct and all related space in one block. */
 	fakeentry = palloc0(sizeof(FakeRelCacheEntryData));
 	rel = (Relation) fakeentry;
@@ -403,6 +405,9 @@ CreateFakeRelcacheEntry(RelFileNode rnode)
 	/* We will never be working with temp rels during recovery */
 	rel->rd_backend = InvalidBackendId;
 
+	/* It must be a permanent table if we're in recovery. */
+	rel->rd_rel->relpersistence = RELPERSISTENCE_PERMANENT;
+
 	/* We don't know the name of the relation; use relfilenode instead */
 	sprintf(RelationGetRelationName(rel), "%u", rnode.relNode);
 
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
@@ -271,6 +271,8 @@ ReadBufferWithoutRelcache(RelFileNode rnode, ForkNumber forkNum,
 
 	SMgrRelation smgr = smgropen(rnode, InvalidBackendId);
 
+	Assert(InRecovery);
+
 	return ReadBuffer_common(smgr, RELPERSISTENCE_PERMANENT, forkNum, blockNum,
 							 mode, strategy, &hit);
 }

Original file line number	Diff line number	Diff line change
`@@ -271,6 +271,8 @@ ReadBufferWithoutRelcache(RelFileNode rnode, ForkNumber forkNum,`
`271`	`271`
`272`	`272`	`SMgrRelation smgr = smgropen(rnode, InvalidBackendId);`
`273`	`273`
	`274`	`+ Assert(InRecovery);`
	`275`	`+`
`274`	`276`	`return ReadBuffer_common(smgr, RELPERSISTENCE_PERMANENT, forkNum, blockNum,`
`275`	`277`	`mode, strategy, &hit);`
`276`	`278`	`}`