Horton

Re: row filtering for logical replication

Greg Nancarrow <gregn4422@gmail.com>

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From: Greg Nancarrow <gregn4422@gmail.com>
To: "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>
Cc: Ajin Cherian <itsajin@gmail.com>, Peter Smith <smithpb2250@gmail.com>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Dilip Kumar <dilipbalaut@gmail.com>, Euler Taveira <euler@eulerto.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 Kapila <amit.kapila16@gmail.com>, Amit Langote <amitlangote09@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-11-17T10:46:10Z
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 Tue, Nov 16, 2021 at 7:33 PM tanghy.fnst@fujitsu.com
<tanghy.fnst@fujitsu.com> wrote:
>
> On Friday, November 12, 2021 6:20 PM Ajin Cherian <itsajin@gmail.com> wrote:
> >
> > Attaching version 39-
> >
>
> I met another problem when filtering out with the operator '~'.
> Data can't be replicated as expected.
>
> For example:
> -- publisher
> create table t (a text primary key);
> create publication pub for table t where (a ~ 'aaa');
>
> -- subscriber
> create table t (a text primary key);
> create subscription sub connection 'port=5432' publication pub;
>
> -- publisher
> insert into t values ('aaaaab');
> insert into t values ('aaaaabc');
> postgres=# select * from t where (a ~ 'aaa');
>     a
> ---------
>  aaaaab
>  aaaaabc
> (2 rows)
>
> -- subscriber
> postgres=# select * from t;
>    a
> --------
>  aaaaab
> (1 row)
>
> The second record can’t be replicated.
>
> By the way, when only applied 0001 patch, I couldn't reproduce this bug.
> So, I think it was related to the later patches.
>

I found that the problem was caused by allocating the WHERE clause
expression nodes in the wrong memory context (so they'd end up getting
freed after first-time use).

The following additions are needed in pgoutput_row_filter_init()  - patch 0005.

+ oldctx = MemoryContextSwitchTo(CacheMemoryContext);
  rfnode = stringToNode(TextDatumGetCString(rfdatum));
  rfnodes = lappend(rfnodes, rfnode);
+ MemoryContextSwitchTo(oldctx);

(these changes are needed in addition to the fixes I posted on this
thread for the crash problem that was previously reported)


Regards,
Greg Nancarrow
Fujitsu Australia