Re: Add a perl function in Cluster.pm to generate WAL

Mmm. It seems like the email I thought I'd sent failed to go out.

At Sun, 11 Jun 2023 07:14:54 +0530, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> wrote in 
> On Wed, Aug 24, 2022 at 6:42 AM Kyotaro Horiguchi
> <horikyota.ntt@gmail.com> wrote:
> >
> > At Tue, 16 Aug 2022 18:40:49 +0200, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote in
> > > On 2022-Aug-16, Andrew Dunstan wrote:
> > > Yeah, I agree with that for advance_wal.  Regarding find_in_log, that
> > > one seems general enough to warrant being in Cluster.pm -- consider
> > > issues_sql_like, which also slurps_file($log).  That could be unified a
> > > little bit, I think.
> >
> > +1
> 
> With the generalized function for find_in_log() has been added as part
> of https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=e25e5f7fc6b74c9d4ce82627e9145ef5537412e2,
> I'm proposing a generalized function for advance_wal(). Please find
> the attached patch.
> 
> I tried to replace the existing tests with the new cluster function
> advance_wal(). Please let me know if I'm missing any other tests.
> Also, this new function can be used by an in-progress feature -
> https://commitfest.postgresql.org/43/3663/.
> 
> Thoughts?

Thanks!

+			"CREATE TABLE tt (); DROP TABLE tt; SELECT pg_switch_wal();");

At least since 11, we can utilize pg_logical_emit_message() for this
purpose. It's more lightweight and seems appropriate, not only because
it doesn't cause any side effects but also bacause we don't have to
worry about name conflicts.


-		 SELECT 'finished';",
-		timeout => $PostgreSQL::Test::Utils::timeout_default));
-is($result[1], 'finished', 'check if checkpoint command is not blocked');
-
+$node_primary2->advance_wal(1);
+$node_primary2->safe_psql('postgres', 'CHECKPOINT;');

This test anticipates that the checkpoint could get blocked. Shouldn't
we keep the timeout?


-$node_primary->safe_psql(
-	'postgres', "create table retain_test(a int);
-									 select pg_switch_wal();
-									 insert into retain_test values(1);
-									 checkpoint;");
+$node_primary->advance_wal(1);
+$node_primary->safe_psql('postgres', "checkpoint;");

The original test generated some WAL after the segment switch, which
appears to be a significant characteristics of the test.

regards.

-- 
Kyotaro Horiguchi
NTT Open Source Software Center