Use ereport not elog for some corrupt-HOT-chain reports.

These errors have been seen in the field in corrupted-data situations.
It seems worthwhile to report them with ERRCODE_DATA_CORRUPTED, rather
than the generic ERRCODE_INTERNAL_ERROR, for the benefit of log monitoring
and tools like amcheck.  However, use errmsg_internal so that the text
strings still aren't translated; it seems unlikely to be worth
translators' time to do so.

Back-patch to 9.3, like the predecessor commit d70cf811f that introduced
these elog calls originally (replacing Asserts).

Peter Geoghegan

Discussion: https://postgr.es/m/CAH2-Wzmn4-Pg-UGFwyuyK-wiTih9j32pwg_7T9iwqXpAUZr=Mg@mail.gmail.com

src/backend/catalog/index.c

@@ -2862,9 +2862,12 @@ IndexBuildHeapRangeScan(Relation heapRelation,
 			offnum = ItemPointerGetOffsetNumber(&heapTuple->t_self);
 
 			if (!OffsetNumberIsValid(root_offsets[offnum - 1]))
-				elog(ERROR, "failed to find parent tuple for heap-only tuple at (%u,%u) in table \"%s\"",
-					 ItemPointerGetBlockNumber(&heapTuple->t_self),
-					 offnum, RelationGetRelationName(heapRelation));
+				ereport(ERROR,
+						(errcode(ERRCODE_DATA_CORRUPTED),
+						 errmsg_internal("failed to find parent tuple for heap-only tuple at (%u,%u) in table \"%s\"",
+										 ItemPointerGetBlockNumber(&heapTuple->t_self),
+										 offnum,
+										 RelationGetRelationName(heapRelation))));
 
 			ItemPointerSetOffsetNumber(&rootTuple.t_self,
 									   root_offsets[offnum - 1]);
@@ -3327,10 +3330,12 @@ validate_index_heapscan(Relation heapRelation,
 		{
 			root_offnum = root_offsets[root_offnum - 1];
 			if (!OffsetNumberIsValid(root_offnum))
-				elog(ERROR, "failed to find parent tuple for heap-only tuple at (%u,%u) in table \"%s\"",
-					 ItemPointerGetBlockNumber(heapcursor),
-					 ItemPointerGetOffsetNumber(heapcursor),
-					 RelationGetRelationName(heapRelation));
+				ereport(ERROR,
+						(errcode(ERRCODE_DATA_CORRUPTED),
+						 errmsg_internal("failed to find parent tuple for heap-only tuple at (%u,%u) in table \"%s\"",
+										 ItemPointerGetBlockNumber(heapcursor),
+										 ItemPointerGetOffsetNumber(heapcursor),
+										 RelationGetRelationName(heapRelation))));
 			ItemPointerSetOffsetNumber(&rootTuple, root_offnum);
 		}