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>
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>, "Shlok Kyal" <shlok.kyal.oss@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: 2024-04-29T11:53:19Z
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 Mon, Apr 29, 2024, at 6:56 AM, Amit Kapila wrote:
> On Wed, Mar 27, 2024 at 1:47 AM Euler Taveira <euler@eulerto.com> wrote:
> >
> > On Tue, Mar 26, 2024, at 4:12 PM, Tomas Vondra wrote:
> >
> > Perhaps I'm missing something, but why is NUM_CONN_ATTEMPTS even needed?
> > Why isn't recovery_timeout enough to decide if wait_for_end_recovery()
> > waited long enough?
> >
> >
> > It was an attempt to decoupled a connection failure (that keeps streaming the
> > WAL) from recovery timeout. The NUM_CONN_ATTEMPTS guarantees that if the primary
> > is gone during the standby recovery process, there is a way to bail out.
> >
> 
> I think we don't need to check primary if the WAL corresponding to
> consistent_lsn is already present on the standby. Shouldn't we first
> check that? Once we ensure that the required WAL is copied, just
> checking server_is_in_recovery() should be sufficient. I feel that
> will be a direct way of ensuring what is required rather than
> indirectly verifying the same (by checking pg_stat_wal_receiver) as we
> are doing currently.

How would you check it? WAL file? During recovery, you are not allowed to use
pg_current_wal_lsn.

Tomas suggested to me off-list that we should adopt a simple solution in
wait_for_end_recovery: wait for recovery_timeout without additional checks
(which means remove the pg_stat_wal_receiver logic).  When we have additional
information that we can reliably use in this function, we can add it. Hence, it
is also easy to adjust the PG_TEST_TIMEOUT_DEFAULT to have stable tests.


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