Fix parallel query on standby servers.

Without this fix, it inevitably bombs out with "ERROR:  failed to
initialize transaction_read_only to 0".  Repair.

Ashutosh Sharma; comments adjusted by me.

diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index 903b3a631334a2aae23dc16e924189c2bd127182..f801faacd29c541d36ba9a49d8108dc85e4838f1 100644 (file)
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -482,11 +482,13 @@ show_log_timezone(void)
  * nothing since XactReadOnly will be reset by the next StartTransaction().
  * The IsTransactionState() test protects us against trying to check
  * RecoveryInProgress() in contexts where shared memory is not accessible.
+ * (Similarly, if we're restoring state in a parallel worker, just allow
+ * the change.)
  */
 bool
 check_transaction_read_only(bool *newval, void **extra, GucSource source)
 {
-       if (*newval == false && XactReadOnly && IsTransactionState())
+       if (*newval == false && XactReadOnly && IsTransactionState() && !InitializingParallelWorker)
        {
                /* Can't go to r/w mode inside a r/o transaction */
                if (IsSubTransaction())