Re: row filtering for logical replication

Erik Rijkers <er@xs4all.nl>

From: Erik Rijkers <er@xs4all.nl>

To: Euler Taveira <euler@timbira.com.br>

Cc: pgsql-hackers <pgsql-hackers@postgresql.org>

Date: 2018-03-01T15:27:11Z

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 2018-03-01 00:03, Euler Taveira wrote:
> The attached patches add support for filtering rows in the publisher.

> 001-Refactor-function-create_estate_for_relation.patch
> 0002-Rename-a-WHERE-node.patch
> 0003-Row-filtering-for-logical-replication.patch

> Comments?

Very, very useful.  I really do hope this patch survives the 
late-arrival-cull.

I built this functionality into a test program I have been using and in 
simple cascading replication tests it works well.

I did find what I think is a bug (a bug easy to avoid but also easy to 
run into):
The test I used was to cascade 3 instances (all on one machine) from 
A->B->C
I ran a pgbench session in instance A, and used:
   in A: alter publication pub0_6515 add table pgbench_accounts where 
(aid between 40000 and 60000-1);
   in B: alter publication pub1_6516 add table pgbench_accounts;

The above worked well, but when I did the same but used the filter in 
both publications:
   in A: alter publication pub0_6515 add table pgbench_accounts where 
(aid between 40000 and 60000-1);
   in B: alter publication pub1_6516 add table pgbench_accounts where 
(aid between 40000 and 60000-1);

then the replication only worked for (pgbench-)scale 1 (hence: very 
little data); with larger scales it became slow (taking many minutes 
where the above had taken less than 1 minute), and ended up using far 
too much memory (or blowing up/crashing altogether).  Something not 
quite right there.

Nevertheless, I am much in favour of acquiring this functionality as 
soon as possible.

Thanks,

Erik Rijkers