Hi,
On Thu, Feb 15, 2024 at 12:48:16PM -0800, Noah Misch wrote:
> On Wed, Feb 14, 2024 at 03:31:16PM +0000, Bertrand Drouvot wrote:
> > What about creating a sub, say wait_for_restart_lsn_calculation() in
> > Cluster.pm
> > and then make use of it in create_logical_slot_on_standby() and above?
> > (something
> > like wait_for_restart_lsn_calculation-v1.patch attached).
>
> Waiting for restart_lsn is just a prerequisite for calling
> pg_log_standby_snapshot(), so I wouldn't separate those two.
Yeah, makes sense.
> If we're
> extracting a sub, I would move the pg_log_standby_snapshot() call into the sub
> and make the API like one of these:
>
> $standby->wait_for_subscription_starting_point($primary, $slot_name);
> $primary->log_standby_snapshot($standby, $slot_name);
>
> Would you like to finish the patch in such a way?
Sure, please find attached standby-slot-test-2-race-v2.patch doing so. I used
log_standby_snapshot() as it seems more generic to me.
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
diff --git a/src/test/perl/PostgreSQL/Test/Cluster.pm b/src/test/perl/PostgreSQL/Test/Cluster.pm
index 07da74cf56..5d3174d0b5 100644
--- a/src/test/perl/PostgreSQL/Test/Cluster.pm
+++ b/src/test/perl/PostgreSQL/Test/Cluster.pm
@@ -3181,6 +3181,37 @@ $SIG{TERM} = $SIG{INT} = sub {
=pod
+=item $node->log_standby_snapshot(self, standby, slot_name)
+
+Log a standby snapshot on primary once the slot restart_lsn is determined on
+the standby.
+
+=cut
+
+sub log_standby_snapshot
+{
+ my ($self, $standby, $slot_name) = @_;
+ my ($stdout, $stderr);
+
+ # Once the slot's restart_lsn is determined, the standby looks for
+ # xl_running_xacts WAL record from the restart_lsn onwards. First wait
+ # until the slot restart_lsn is determined.
+
+ $standby->poll_query_until(
+ 'postgres', qq[
+ SELECT restart_lsn IS NOT NULL
+ FROM pg_catalog.pg_replication_slots WHERE slot_name = '$slot_name'
+ ])
+ or die
+ "timed out waiting for logical slot to calculate its restart_lsn";
+
+ # Then arrange for the xl_running_xacts record for which the standby is
+ # waiting.
+ $self->safe_psql('postgres', 'SELECT pg_log_standby_snapshot()');
+}
+
+=pod
+
=item $node->create_logical_slot_on_standby(self, primary, slot_name, dbname)
Create logical replication slot on given standby
@@ -3206,21 +3237,9 @@ sub create_logical_slot_on_standby
'2>',
\$stderr);
- # Once the slot's restart_lsn is determined, the standby looks for
- # xl_running_xacts WAL record from the restart_lsn onwards. First wait
- # until the slot restart_lsn is determined.
-
- $self->poll_query_until(
- 'postgres', qq[
- SELECT restart_lsn IS NOT NULL
- FROM pg_catalog.pg_replication_slots WHERE slot_name = '$slot_name'
- ])
- or die
- "timed out waiting for logical slot to calculate its restart_lsn";
-
- # Then arrange for the xl_running_xacts record for which pg_recvlogical is
+ # Arrange for the xl_running_xacts record for which pg_recvlogical is
# waiting.
- $primary->safe_psql('postgres', 'SELECT pg_log_standby_snapshot()');
+ $primary->log_standby_snapshot($self, $slot_name);
$handle->finish();
diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index b020361b29..0710bccc17 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -465,8 +465,8 @@ $psql_subscriber{subscriber_stdin} .= "\n";
$psql_subscriber{run}->pump_nb();
-# Speed up the subscription creation
-$node_primary->safe_psql('postgres', "SELECT pg_log_standby_snapshot()");
+# Log the standby snapshot to speed up the subscription creation
+$node_primary->log_standby_snapshot($node_standby, 'tap_sub');
# Explicitly shut down psql instance gracefully - to avoid hangs
# or worse on windows
