Horton

Re: Data is copied twice when specifying both child and parent table in publication

Greg Nancarrow <gregn4422@gmail.com>

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From: Greg Nancarrow <gregn4422@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Amit Langote <amitlangote09@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, Dilip Kumar <dilipbalaut@gmail.com>
Date: 2021-12-01T23:21:39Z
Lists: pgsql-hackers 
On Wed, Dec 1, 2021 at 10:15 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> Thanks, your patch looks good to me. I have slightly changed the
> comments and commit message in the attached.
>

I'd suggest tidying the patch comment a bit:

"We publish the child table's data twice for a publication that has both
child and parent tables and is published with publish_via_partition_root
as true. This happens because subscribers will initiate synchronization
using both parent and child tables, since it gets both as separate tables
in the initial table list."

Also, perhaps the following additional comment (or similar) could be
added to the pg_publication_tables documentation in catalogs.sgml:

For publications of partitioned tables with publish_via_partition_root
set to true, the partitioned table itself (rather than the individual
partitions) is included in the view.

> I think we should back-patch this but I am slightly worried ...

I'd be in favor of back-patching this.


Regards,
Greg Nancarrow
Fujitsu Australia

Commits

  1. Avoid syncing data twice for the 'publish_via_partition_root' option.

  2. Fix partition table's REPLICA IDENTITY checking on the subscriber.

  3. Prohibit combining publications with different column lists.

  4. Fix double publish of child table's data.

  5. Support adding partitioned tables to publication