Horton

Re: speed up a logical replica setup

Euler Taveira <euler@eulerto.com>

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From: "Euler Taveira" <euler@eulerto.com>
To: "Amit Kapila" <amit.kapila16@gmail.com>, "Shlok Kyal" <shlok.kyal.oss@gmail.com>
Cc: "Tomas Vondra" <tomas.vondra@enterprisedb.com>, "kuroda.hayato@fujitsu.com" <kuroda.hayato@fujitsu.com>, "Peter Eisentraut" <peter@eisentraut.org>, "Bharath Rupireddy" <bharath.rupireddyforpostgres@gmail.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, "Michael Paquier" <michael@paquier.xyz>, "Andres Freund" <andres@anarazel.de>, "Ashutosh Bapat" <ashutosh.bapat.oss@gmail.com>, Fabrízio de Royes Mello <fabriziomello@gmail.com>, "vignesh C" <vignesh21@gmail.com>
Date: 2024-05-22T15:16:24Z
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 →

  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 Wed, May 22, 2024, at 8:19 AM, Amit Kapila wrote:
> >
> > v2-0001: not changed
> >
> 
> Shouldn't we modify it as per the suggestion given in the email [1]? I
> am wondering if we can entirely get rid of checking the primary
> business and simply rely on recovery_timeout and keep checking
> server_is_in_recovery(). If so, we can modify the test to use
> non-default recovery_timeout (say 180s or something similar if we have
> used it at any other place). As an additional check we can ensure that
> constent_lsn is present on standby.

That's exactly what I want to propose as Tomas convinced me offlist that less is
better when we don't have a useful recovery progress reporting mechanism to make
sure it is still working on the recovery and we should wait.

> > v2-0002: not changed
> >
> 
> We have added more tries to see if the primary_slot_name becomes
> active but I think it is still fragile because it is possible on slow
> machines that the required slot didn't become active even after more
> retries. I have raised the same comment previously [2] and asked an
> additional question but didn't get any response.

Following the same line that simplifies the code, we can: (a) add a loop in
check_subscriber() that waits until walreceiver is available on subscriber or
(b) use a timeout. The main advantage of (a) is that the primary slot is already
available but I'm afraid we need a escape mechanism for the loop (timeout?).

I'll summarize all issues as soon as I finish the review of sync slot support. I
think we should avoid new development if we judge that the item can be
documented as a limitation for this version. Nevertheless, I will share patches
so you can give your opinion on whether it is an open item or new development.


--
Euler Taveira
EDB   https://www.enterprisedb.com/