Fix wal_consistency_checking nbtree bug.

petergeoghegan · petergeoghegan · commit efc5dcfd8ad4 · 2020-11-05T15:01:40.000-08:00
wal_consistency_checking indicated an inconsistency in certain cases involving nbtree page deletion. The underlying issue is that there was a minor difference between the page image produced after a REDO routine ran and the corresponding page image following original execution. This harmless inconsistency has been around forever. We more or less expect total consistency among even deleted nbtree pages these days, though, so this won't do anymore. To fix, tweak the REDO routine to match original execution. Oversight in commit f47b5e1.
diff --git a/src/backend/access/nbtree/nbtxlog.c b/src/backend/access/nbtree/nbtxlog.c
@@ -824,6 +824,8 @@ btree_xlog_unlink_page(uint8 info, XLogReaderState *record)
 	pageop->btpo_next = rightsib;
 	pageop->btpo.xact = xlrec->btpo_xact;
 	pageop->btpo_flags = BTP_DELETED;
+	if (!BlockNumberIsValid(xlrec->topparent))
+		pageop->btpo_flags |= BTP_LEAF;
 	pageop->btpo_cycleid = 0;
 
 	PageSetLSN(page, lsn);
