Re: row filtering for logical replication

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