Horton

RE: speed up a logical replica setup

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

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From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
To: 'Amit Kapila' <amit.kapila16@gmail.com>
Cc: Euler Taveira <euler@eulerto.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, Andres Freund <andres@anarazel.de>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Michael Paquier <michael@paquier.xyz>, Peter Eisentraut <peter@eisentraut.org>
Date: 2024-01-08T07:05:21Z
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

Dear Amit,

> On Fri, Jan 5, 2024 at 3:36 PM Hayato Kuroda (Fujitsu)
> <kuroda.hayato@fujitsu.com> wrote:
> >
> > I love your proposal, so I want to join the review. Here are my first comments.
> >
> > 01.
> > Should we restrict that `--subscriber-conninfo` must not have hostname or IP?
> > We want users to execute pg_subscriber on the target, right?
> >
> 
> I don't see any harm in users giving those information but we should
> have some checks to ensure that the server is in standby mode and is
> running locally. The other related point is do we need to take input
> for the target cluster directory from the user? Can't we fetch that
> information once we are connected to standby?

I think that functions like inet_client_addr() may be able to use, but it returns
NULL only when the connection is via a Unix-domain socket. Can we restrict
pg_subscriber to use such a socket?

> >
> > 05.
> > I found that the connection string for each subscriptions have a setting
> > "fallback_application_name=pg_subscriber". Can we remove it?
> >
> > ```
> > postgres=# SELECT subconninfo FROM pg_subscription;
> >                                    subconninfo
> >
> ---------------------------------------------------------------------------------
> >  user=postgres port=5431 fallback_application_name=pg_subscriber
> dbname=postgres
> > (1 row)
> > ```
> 
> Can that help distinguish the pg_subscriber connection on the publisher?
>

Note that this connection string is used between the publisher instance and the
subscriber instance (not pg_subscriber client application). Also, the
fallback_application_name would be replaced to the name of subscriber in
run_apply_worker()->walrcv_connect(). Actually the value would not be used.
See below output on publisher.

```
publisher=# SELECT application_name, backend_type FROM pg_stat_activity where backend_type = 'walsender';
   application_name   | backend_type 
----------------------+--------------
 pg_subscriber_5_9411 | walsender
(1 row)
```

Or, if you mean to say that this can distinguish whether the subscription is used
by pg_subscriber or not. I think it is sufficient the current format of name.

Best Regards,
Hayato Kuroda
FUJITSU LIMITED