Re: row filtering for logical replication

Amit Kapila <amit.kapila16@gmail.com>

From: Amit Kapila <amit.kapila16@gmail.com>

To: Dilip Kumar <dilipbalaut@gmail.com>

Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Greg Nancarrow <gregn4422@gmail.com>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Euler Taveira <euler@eulerto.com>, Peter Smith <smithpb2250@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>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Amit Langote <amitlangote09@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2021-07-20T09:00:07Z

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 →

Release cache tuple when no longer needed
- ed0fbc8e5ac9 15.0 landed
Add some additional tests for row filters in logical replication.
- ceb57afd3ce1 15.0 landed
Fix one of the tests introduced in commit 52e4f0cd47.
- cfb4e209ec15 15.0 landed
Allow specifying row filters for logical replication of tables.
- 52e4f0cd472d 15.0 landed
Move scanint8() to numutils.c
- cfc7191dfea3 15.0 cited
Replace Test::More plans with done_testing
- 549ec201d613 15.0 cited
Reduce relcache access in WAL sender streaming logical changes
- 6ce16088bfed 15.0 cited
Small cleanups related to PUBLICATION framework code
- c9105dd3660f 15.0 cited
Add a view to show the stats of subscription workers.
- 8d74fc96db5f 15.0 cited
Allow publishing the tables of schema.
- 5a2832465fd8 15.0 cited
Doc: improve documentation of CREATE/ALTER SUBSCRIPTION.
- 1882d6cca161 15.0 cited
Add PublicationTable and PublicationRelInfo structs
- 0c6828fa987b 15.0 cited
Remove unused argument "txn" in maybe_send_schema().
- 93d573d86571 15.0 cited
Add prepare API support for streaming transactions in logical replication.
- 63cf61cdeb7b 15.0 cited
Unify PostgresNode's new() and get_new_node() methods
- 201a76183e20 15.0 cited
Use l*_node() family of functions where appropriate
- 2b00db4fb0c7 15.0 cited
Add support for prepared transactions to built-in logical replication.
- a8fd13cab0ba 15.0 cited
Restore the portal-level snapshot after procedure COMMIT/ROLLBACK.
- ef9480509622 11.13 cited
Rename a parse node to be more general
- 91d1f2d30210 14.0 landed
Remove unused column atttypmod from initial tablesync query
- 4ad31bb2ef25 14.0 landed
SEARCH and CYCLE clauses
- 3696a600e229 14.0 cited

On Tue, Jul 20, 2021 at 9:54 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Mon, Jul 19, 2021 at 4:31 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> >
> > On Mon, Jul 19, 2021 at 3:12 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > > > Maybe a second option is to have replication change any UPDATE into
> > > > either an INSERT or a DELETE, if the old or the new row do not pass the
> > > > filter, respectively.  That way, the databases would remain consistent.
> >
> > Yeah, I think this is the best way to keep the data consistent.
> >
>
> Today, while studying the behavior of this particular operation in
> other databases, I found that IBM's InfoSphere Data Replication does
> exactly this. See [1]. I think there is a merit if want to follow this
> idea.
>

As per my initial analysis, there shouldn't be much difficulty in
implementing this behavior. We need to change the filter API
(pgoutput_row_filter) such that it tells us whether the filter is
satisfied by the old row, new row or both and then the caller should
be able to make a decision based on that. I think that should be
sufficient to turn update to insert/delete when required. I might be
missing something here but this doesn't appear to require any drastic
changes in the patch.

-- 
With Regards,
Amit Kapila.