On 20/08/2025 03:37, Noah Misch wrote:
On Tue, Aug 19, 2025 at 11:45:01PM +0300, Heikki Linnakangas wrote:
How about the attached, then? It reverts the GetTransactionSnapshot()
change. But to still catch at least some of the invalid uses of the historic
snapshot, it adds checks to heap_beginscan() and index_beginscan(), to
complain if they are called on a non-catalog relation with a historic
snapshot.
@@ -1143,6 +1143,15 @@ heap_beginscan(Relation relation, Snapshot snapshot,
if (!(snapshot && IsMVCCSnapshot(snapshot)))
scan->rs_base.rs_flags &= ~SO_ALLOW_PAGEMODE;
+ /* Check that a historic snapshot is not used for non-catalog tables */
+ if (snapshot &&
+ IsHistoricMVCCSnapshot(snapshot) &&
+ !RelationIsAccessibleInLogicalDecoding(relation))
+ {
+ elog(ERROR, "cannot query non-catalog table \"%s\" during logical
decoding",
+ RelationGetRelationName(relation));
+ }
+
I feel post-beta3 is late for debut of restrictions like this. How about a
pure revert, then add those restrictions in v19? Should be s/elog/ereport/,
also.
Ok, fair. I committed the revert to v18, and the revert + additional
checks to master.
- Heikki
