Fix description of WAL record XLOG_BTREE_META_CLEANUP

michaelpq · michaelpq · commit 6dfc9464472e · 2019-06-19T11:02:28.000+09:00
This record uses one metadata buffer and registers some data associated to the buffer, but when parsing the record for its description a direct access to the record data was done, but there is none. This leads usually to an incorrect description, but can also cause crashes like in pg_waldump. Instead, fix things so as the parsing uses the data associated to the metadata block. This is an oversight from 3d92796, so backpatch down to 11. Author: Michael Paquier Description: https://postgr.es/m/20190617013059.GA3153@paquier.xyz Backpatch-through: 11
diff --git a/src/backend/access/rmgrdesc/nbtdesc.c b/src/backend/access/rmgrdesc/nbtdesc.c
@@ -98,8 +98,10 @@ btree_desc(StringInfo buf, XLogReaderState *record)
 			}
 		case XLOG_BTREE_META_CLEANUP:
 			{
-				xl_btree_metadata *xlrec = (xl_btree_metadata *) rec;
+				xl_btree_metadata *xlrec;
 
+				xlrec = (xl_btree_metadata *) XLogRecGetBlockData(record, 0,
+																  NULL);
 				appendStringInfo(buf, "oldest_btpo_xact %u; last_cleanup_num_heap_tuples: %f",
 								 xlrec->oldest_btpo_xact,
 								 xlrec->last_cleanup_num_heap_tuples);

Original file line number	Diff line number	Diff line change
`@@ -98,8 +98,10 @@ btree_desc(StringInfo buf, XLogReaderState *record)`
`98`	`98`	`}`
`99`	`99`	`case XLOG_BTREE_META_CLEANUP:`
`100`	`100`	`{`
`101`		`- xl_btree_metadata xlrec = (xl_btree_metadata ) rec;`
	`101`	`+ xl_btree_metadata *xlrec;`
`102`	`102`
	`103`	`+ xlrec = (xl_btree_metadata *) XLogRecGetBlockData(record, 0,`
	`104`	`+ NULL);`
`103`	`105`	`appendStringInfo(buf, "oldest_btpo_xact %u; last_cleanup_num_heap_tuples: %f",`
`104`	`106`	`xlrec->oldest_btpo_xact,`
`105`	`107`	`xlrec->last_cleanup_num_heap_tuples);`