Fix the same-rel optimization when creating WAL records.

hlinnaka · hlinnaka · commit ec3d976bce7e · 2015-05-04T21:03:36.000+03:00
prev_regbuf was never set, and therefore the same-rel flag was never set on
WAL records.

Report and fix by Zhanq Zq
diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/transam/xloginsert.c
@@ -667,10 +667,10 @@ XLogRecordAssemble(RmgrId rmid, uint8 info,
 		{
 			samerel = true;
 			bkpb.fork_flags |= BKPBLOCK_SAME_REL;
-			prev_regbuf = regbuf;
 		}
 		else
 			samerel = false;
+		prev_regbuf = regbuf;
 
 		/* Ok, copy the header to the scratch buffer */
 		memcpy(scratch, &bkpb, SizeOfXLogRecordBlockHeader);

Original file line number	Diff line number	Diff line change
`@@ -667,10 +667,10 @@ XLogRecordAssemble(RmgrId rmid, uint8 info,`
`667`	`667`	`{`
`668`	`668`	`samerel = true;`
`669`	`669`	`bkpb.fork_flags \|= BKPBLOCK_SAME_REL;`
`670`		`- prev_regbuf = regbuf;`
`671`	`670`	`}`
`672`	`671`	`else`
`673`	`672`	`samerel = false;`
	`673`	`+ prev_regbuf = regbuf;`
`674`	`674`
`675`	`675`	`/* Ok, copy the header to the scratch buffer */`
`676`	`676`	`memcpy(scratch, &bkpb, SizeOfXLogRecordBlockHeader);`