nbtree VACUUM: cope with topparent inconsistencies.

petergeoghegan · petergeoghegan · commit 355917c07c63 · 2023-06-21T17:41:50.000-07:00
Avoid "right sibling %u of block %u is not next child" errors when vacuuming a corrupt nbtree index. Just LOG the issue and press on. That way VACUUM will have a decent chance of finishing off all required processing for the index (and for the table as a whole). This is similar to recent work from commit 5abff19, as well as work from commit 5b861ba (later backpatched as commit 43e409c), which taught nbtree VACUUM to keep going when its "re-find" check fails. The hardening added by this commit takes place directly after the "re-find" check, right before the critical section for the first stage of page deletion. Author: Peter Geoghegan <pg@bowt.ie> Discussion: https://postgr.es/m/CAH2-Wz=dayg0vjs4+er84TS9ami=csdzjpuiCGbEw=idhwqhzQ@mail.gmail.com Backpatch: 11- (all supported versions).
diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c
@@ -1686,9 +1686,19 @@ _bt_mark_page_halfdead(Relation rel, Buffer leafbuf, BTStack stack)
 	itemid = PageGetItemId(page, nextoffset);
 	itup = (IndexTuple) PageGetItem(page, itemid);
 	if (BTreeInnerTupleGetDownLink(itup) != rightsib)
-		elog(ERROR, "right sibling %u of block %u is not next child %u of block %u in index \"%s\"",
-			 rightsib, target, BTreeInnerTupleGetDownLink(itup),
-			 BufferGetBlockNumber(topparent), RelationGetRelationName(rel));
+	{
+		ereport(LOG,
+				(errcode(ERRCODE_INDEX_CORRUPTED),
+				 errmsg_internal("right sibling %u of block %u is not next child %u of block %u in index \"%s\"",
+								 rightsib, target,
+								 BTreeInnerTupleGetDownLink(itup),
+								 BufferGetBlockNumber(topparent),
+								 RelationGetRelationName(rel))));
+
+		_bt_relbuf(rel, topparent);
+
+		return false;
+	}
 
 	/*
 	 * Any insert which would have gone on the leaf block will now go to its
