Horton

Re: row filtering for logical replication

Euler Taveira <euler@eulerto.com>

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From: "Euler Taveira" <euler@eulerto.com>
To: "Tomas Vondra" <tomas.vondra@enterprisedb.com>, "Jeff Davis" <pgsql@j-davis.com>, "Amit Kapila" <amit.kapila16@gmail.com>
Cc: "Alvaro Herrera" <alvherre@alvh.no-ip.org>, "Greg Nancarrow" <gregn4422@gmail.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: 2021-07-13T21:02:43Z
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, Jul 13, 2021, at 4:07 PM, Tomas Vondra wrote:
> On 7/13/21 5:44 PM, Jeff Davis wrote:
> > On Tue, 2021-07-13 at 10:24 +0530, Amit Kapila wrote:
8<

> >> (c) the columns
> >> referred to in the filter should be part of PK or Replica Identity.
> > 
> > Why?
> > 
> 
> I'm not sure either.
This patch uses the old row for DELETE operations and new row for INSERT and
UPDATE operations. Since we usually don't use REPLICA IDENTITY FULL, all
columns in an old row that are not part of the PK or REPLICA IDENTITY are NULL.
The row filter evaluates NULL to false. Documentation says

  <para>
   The <literal>WHERE</literal> clause should contain only columns that are
   part of the primary key or be covered  by <literal>REPLICA
   IDENTITY</literal> otherwise, <command>DELETE</command> operations will not
   be replicated. That's because old row is used and it only contains primary
   key or columns that are part of the <literal>REPLICA IDENTITY</literal>; the
   remaining columns are <literal>NULL</literal>. For <command>INSERT</command>
   and <command>UPDATE</command> operations, any column might be used in the
   <literal>WHERE</literal> clause. New row is used and it contains all
   columns. A <literal>NULL</literal> value causes the expression to evaluate
   to false; avoid using columns without not-null constraints in the
   <literal>WHERE</literal> clause. The <literal>WHERE</literal> clause does
   not allow functions and user-defined operators.
  </para>


--
Euler Taveira
EDB   https://www.enterprisedb.com/