Re: Fixing WAL instability in various TAP tests

I wrote:
> So there's more than one symptom, but in any case it seems like
> we have an issue in WAL replay.  I wonder whether it's bloom's fault
> or a core bug.

Actually ... I bet it's just the test script's fault.  It waits for the
standby to catch up like this:

    my $caughtup_query =
      "SELECT pg_current_wal_lsn() <= write_lsn FROM pg_stat_replication WHERE application_name = '$applname';";
    $node_primary->poll_query_until('postgres', $caughtup_query)
      or die "Timed out while waiting for standby 1 to catch up";

which seems like completely the wrong condition.  Don't we need the
standby to have *replayed* the WAL, not merely written it to disk?

I'm also wondering why this doesn't use wait_for_catchup, instead
of reinventing the query to use.

            regards, tom lane