Fix rare missing cancellations in Hot Standby.

The machinery around XLOG_HEAP2_CLEANUP_INFO failed
to correctly pass through the necessary information
on latestRemovedXid, avoiding cancellations in some
infrequent concurrent update/cleanup scenarios.

Backpatchable fix to 9.0

Detailed bug report and fix by Noah Misch,
backpatchable version by me.

diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index 3ca332d28f2342752b1372f33ab06cf810a9d6e1..c723119ea808835fae58525e192d0f6471544258 100644 (file)
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -173,7 +173,7 @@ heap_page_prune(Relation relation, Buffer buffer, TransactionId OldestXmin,
         * initialize the rest of our working state.
         */
        prstate.new_prune_xid = InvalidTransactionId;
-       prstate.latestRemovedXid = InvalidTransactionId;
+       prstate.latestRemovedXid = *latestRemovedXid;
        prstate.nredirected = prstate.ndead = prstate.nunused = 0;
        memset(prstate.marked, 0, sizeof(prstate.marked));