Re: Perform streaming logical transactions by background workers and parallel apply

On Mon, Dec 26, 2022 at 9:52 AM houzj(dot)fnst(at)fujitsu(dot)com
<houzj(dot)fnst(at)fujitsu(dot)com> wrote:
>
> On Friday, December 23, 2022 5:20 PM houzj(dot)fnst(at)fujitsu(dot)com <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
>
> Since the GUC used to force stream changes has been committed, I removed that
> patch from the patch set here and rebased the testcases based on that commit.
> Here is the rebased patch set.
>

Few comments on 0002 and 0001 patches
=================================
1.
+ if ($is_parallel)
+ {
+ $node_subscriber->append_conf('postgresql.conf',
+ "log_min_messages = debug1");
+ $node_subscriber->reload;
+ }
+
+ # Check the subscriber log from now on.
+ $offset = -s $node_subscriber->logfile;
+
+ $in .= q{
+ BEGIN;
+ INSERT INTO test_tab SELECT i, md5(i::text) FROM
generate_series(3, 5000) s(i);

How can we guarantee that reload would have taken place before this
next test? I see that 020_archive_status.pl is executing a query to
ensure the reload has been taken into consideration. Can we do the
same?

2. It is not very clear whether converting 017_stream_ddl and
019_stream_subxact_ddl_abort adds much value. They seem to be mostly
testing DDL/DML interaction of publisher side. We can probably check
the code coverage by removing the parallel version for these two files
and remove them unless it covers some extra code. If we decide to
remove parallel version for these two files then we can probably add a
comment atop these files indicating why we don't have a version that
parallel option for these tests.

3.
+# Drop the unique index on the subscriber, now it works.
+$node_subscriber->safe_psql('postgres', "DROP INDEX idx_tab");
+
+# Wait for this streaming transaction to be applied in the apply worker.
$node_publisher->wait_for_catchup($appname);

$result =
- $node_subscriber->safe_psql('postgres',
- "SELECT count(*), count(c), count(d = 999) FROM test_tab");
-is($result, qq(3334|3334|3334), 'check extra columns contain local defaults');
+ $node_subscriber->safe_psql('postgres', "SELECT count(*) FROM test_tab_2");
+is($result, qq(5001), 'data replicated to subscriber after dropping index');

-# Test the streaming in binary mode
+# Clean up test data from the environment.
+$node_publisher->safe_psql('postgres', "TRUNCATE TABLE test_tab_2");
+$node_publisher->wait_for_catchup($appname);
$node_subscriber->safe_psql('postgres',
- "ALTER SUBSCRIPTION tap_sub SET (binary = on)");
+ "CREATE UNIQUE INDEX idx_tab on test_tab_2(a)");

What is the need to first Drop the index and then recreate it after a few lines?

4. Attached, find some comment improvements atop v67-0002* patch.
Similar comments need to be changed in other test files.

5. Attached, find some comment improvements atop v67-0001* patch.

--
With Regards,
Amit Kapila.