Horton

Re: row filtering for logical replication

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Greg Nancarrow <gregn4422@gmail.com>
Cc: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Peter Smith <smithpb2250@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, Euler Taveira <euler@eulerto.com>, vignesh C <vignesh21@gmail.com>, Ajin Cherian <itsajin@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Rahila Syed <rahilasyed90@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Önder Kalacı <onderkalaci@gmail.com>, japin <japinli@hotmail.com>, Michael Paquier <michael@paquier.xyz>, David Steele <david@pgmasters.net>, Craig Ringer <craig@2ndquadrant.com>, Amit Langote <amitlangote09@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-01-24T06:09:23Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Release cache tuple when no longer needed

  2. Add some additional tests for row filters in logical replication.

  3. Fix one of the tests introduced in commit 52e4f0cd47.

  4. Allow specifying row filters for logical replication of tables.

  5. Move scanint8() to numutils.c

  6. Replace Test::More plans with done_testing

  7. Reduce relcache access in WAL sender streaming logical changes

  8. Small cleanups related to PUBLICATION framework code

  9. Add a view to show the stats of subscription workers.

  10. Allow publishing the tables of schema.

  11. Doc: improve documentation of CREATE/ALTER SUBSCRIPTION.

  12. Add PublicationTable and PublicationRelInfo structs

  13. Remove unused argument "txn" in maybe_send_schema().

  14. Add prepare API support for streaming transactions in logical replication.

  15. Unify PostgresNode's new() and get_new_node() methods

  16. Use l*_node() family of functions where appropriate

  17. Add support for prepared transactions to built-in logical replication.

  18. Restore the portal-level snapshot after procedure COMMIT/ROLLBACK.

  19. Rename a parse node to be more general

  20. Remove unused column atttypmod from initial tablesync query

  21. SEARCH and CYCLE clauses

On Mon, Jan 24, 2022 at 10:29 AM Greg Nancarrow <gregn4422@gmail.com> wrote:
>
> On Mon, Jan 24, 2022 at 2:47 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > > (3) pgoutput_row_filter_exec_expr
> > > pgoutput_row_filter_exec_expr() returns false if "isnull" is true,
> > > otherwise (if "isnull" is false) returns the value of "ret"
> > > (true/false).
> > > So the following elog needs to be changed (Peter Smith previously
> > > pointed this out, but it didn't get completely changed):
> > >
> > > BEFORE:
> > > + elog(DEBUG3, "row filter evaluates to %s (isnull: %s)",
> > > + DatumGetBool(ret) ? "true" : "false",
> > > + isnull ? "true" : "false");
> > > AFTER:
> > > + elog(DEBUG3, "row filter evaluates to %s (isnull: %s)",
> > > + isnull ? "false" : DatumGetBool(ret) ? "true" : "false",
> > > + isnull ? "true" : "false");
> > >
> >
> > Do you see any problem with the current? I find the current one easy
> > to understand.
> >
>
> Yes, I see a problem.
>

I tried by inserting NULL value in a column having row filter and the
result it shows is:

 LOG:  row filter evaluates to false (isnull: true)

This is what is expected.

>
> But regression tests fail when that code change is made (indicating
> that there are cases when "isnull" is true but the function returns
> true instead of false).
>

But that is not what I am seeing in Logs with a test case where the
row filter column has NULL values. Could you please try that see what
is printed in LOG?

You can change the code to make the elevel as LOG to get the results
easily. The test case I tried is as follows:
Node-1:
postgres=# create table t1(c1 int, c2 int);
CREATE TABLE
postgres=# create publication pub for table t1 WHERE (c1 > 10);
CREATE PUBLICATION

Node-2:
postgres=# create table t1(c1 int, c2 int);
CREATE TABLE
postgres=# create subscription sub connection 'dbname=postgres' publication pub;
NOTICE:  created replication slot "sub" on publisher
CREATE SUBSCRIPTION

After this on publisher-node, I see the LOG as "LOG:  row filter
evaluates to false (isnull: true)". I have verified that in the code
as well (in slot_deform_heap_tuple), we set the value as 0 for isnull
which matches above observation.


-- 
With Regards,
Amit Kapila.