Horton

Re: speed up a logical replica setup

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Cc: vignesh C <vignesh21@gmail.com>, Euler Taveira <euler@eulerto.com>, pgsql-hackers@lists.postgresql.org, Andres Freund <andres@anarazel.de>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Date: 2024-01-04T11:04:13Z
Lists: pgsql-hackers

Commits

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  1. pg_createsubscriber: Remove obsolete comment

  2. pg_createsubscriber: Fix an unpredictable recovery wait time.

  3. Fix unstable test in 040_pg_createsubscriber.

  4. Fix the testcase introduced in commit 81d20fbf7a.

  5. Further weaken new pg_createsubscriber test on Windows.

  6. Temporarily(?) weaken new pg_createsubscriber test on Windows.

  7. Make pg_createsubscriber warn if publisher has two-phase commit enabled.

  8. Make pg_createsubscriber more wary about quoting connection parameters.

  9. pg_createsubscriber: Remove failover replication slots on subscriber

  10. pg_createsubscriber: Remove replication slot check on primary

  11. pg_createsubscriber: Only --recovery-timeout controls the end of recovery process

  12. pg_createsubscriber: creates a new logical replica from a standby server

  13. Add some const decorations

  14. Add option force_initdb to PostgreSQL::Test::Cluster:init()

  15. Remove MSVC scripts

On Thu, Jan 4, 2024 at 12:30 PM Ashutosh Bapat
<ashutosh.bapat.oss@gmail.com> wrote:
>
> On Wed, Jan 3, 2024 at 2:49 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> >  c) Drop the replication slots d) Drop the
> > > publications
> > >
> >
> > I am not so sure about dropping publications because, unlike
> > subscriptions which can start to pull the data, there is no harm with
> > publications. Similar to publications there could be some user-defined
> > functions or other other objects which may not be required once the
> > standby replica is converted to subscriber. I guess we need to leave
> > those to the user.
> >
>
> IIUC, primary use of pg_subscriber utility is to start a logical
> subscription from a physical base backup (to reduce initial sync time)
> as against logical backup taken while creating a subscription. Hence I
> am expecting that apart from this difference, the resultant logical
> replica should look similar to the logical replica setup using a
> logical subscription sync. Hence we should not leave any replication
> objects around. UDFs (views, and other objects) may have some use on a
> logical replica. We may replicate changes to UDF once DDL replication
> is supported. But what good is having the same publications as primary
> also on logical replica?
>

The one use case that comes to my mind is to set up bi-directional
replication. The publishers want to subscribe to the new subscriber.

-- 
With Regards,
Amit Kapila.