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: Euler Taveira <euler@eulerto.com>
Cc: Shlok Kyal <shlok.kyal.oss@gmail.com>, 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: 2024-05-23T08:54:25Z
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 8:46 PM Euler Taveira <euler@eulerto.com> wrote:
>
> On Wed, May 22, 2024, at 8:19 AM, Amit Kapila wrote:
>
> > 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?).
>

Sorry, it is not clear to me why we need any additional loop in
check_subscriber(), aren't we speaking about the problem in
check_publisher() function?

Why in the first place do we need to ensure that primary_slot_name is
active on the primary? You mentioned something related to WAL
retention but I don't know how that is related to this tool's
functionality. If at all, we are bothered about WAL retention on the
primary that should be the WAL corresponding to consistent_lsn
computed by setup_publisher() but this check doesn't seem to ensure
that.

-- 
With Regards,
Amit Kapila.