Horton

Re: Handle infinite recursion in logical replication setup

vignesh C <vignesh21@gmail.com>

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From: vignesh C <vignesh21@gmail.com>
To: Peter Smith <smithpb2250@gmail.com>
Cc: "kuroda.hayato@fujitsu.com" <kuroda.hayato@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-03-07T05:20:35Z
Lists: pgsql-hackers 
On Mon, Mar 7, 2022 at 10:26 AM Peter Smith <smithpb2250@gmail.com> wrote:
>
> Hi Vignesh, I also have not looked at the patch yet, but I have what
> seems like a very fundamental (and possibly dumb) question...
>
> Basically, I do not understand the choice of syntax for setting things up.
>
> IMO that "only-local" option sounds very similar to the other
> PUBLICATION ("publish") options which decide the kinds of things that
> will be published. So it feels more natural for me to think of the
> publisher as being the one to decide what will be published.
>
> e.g.
>
> option 1:
> CREATE PUBLICATION p1 FOR TABLE t1;
> CREATE SUBSCRITION s1 ... FOR PUBLICATION p1 WITH (only_local = true);
>
> option 2:
> CREATE PUBLICATION p1 FOR TABLE t1 WEHRE (publish = 'only_local');
> CREATE SUBSCRITION s1 ... FOR PUBLICATION p1;
>
> ~~
>
> IIUC the patch is using option 1. My first impression was it feels
> back-to-front for the SUBSCRIPTION telling the PUBLICATION what to
> publish.
>
> So, why does the patch use syntax option 1?

I felt the advantage with keeping it at the subscription side is that,
the subscriber from one node can subscribe with only_local option on
and a different subscriber from a different node can subscribe with
only_local option as off. This might not be possible with having the
option at publisher side. Having it at the subscriber side might give
more flexibility for the user.

Regards,
Vignesh

Commits

  1. Improved CREATE SUBSCRIPTION message for clarity

  2. Fix the test case introduced by commit 8756930190.

  3. Raise a warning if there is a possibility of data from multiple origins.

  4. Add wait_for_subscription_sync for TAP tests.

  5. Bump catversion for commit d8cd0c6c95c0120168df93aae095df4e0682a08a.

  6. Allow users to skip logical replication of data having origin.

  7. Improve two comments related to a boolean DefElem's value

  8. doc: Fix man page whitespace issues