public inbox for [email protected]
help / color / mirror / Atom feedFrom: Andrey Borodin <[email protected]>
To: Bruce Momjian <[email protected]>
Cc: Bharath Rupireddy <[email protected]>
Cc: Kyotaro Horiguchi <[email protected]>
Cc: Laurenz Albe <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: SATYANARAYANA NARLAPURAM <[email protected]>
Subject: Re: An attempt to avoid locally-committed-but-not-replicated-to-standby-transactions in synchronous replication
Date: Tue, 8 Nov 2022 21:06:36 -0800
Message-ID: <CAAhFRxjFGSk-hVTjnpFwm1XBUcHL8Obugt=P+ixV5AD9H+Kkrw@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
<[email protected]>
<CALj2ACWPMYoPSC3t-9uW+0gqDUcJf1mLww6hHzo2V2AvE-Tu+w@mail.gmail.com>
<[email protected]>
<CALj2ACXmMWtpmuT-=v8F+Lk4QCbdkeN+yHKXeRGKFfjG96YbKA@mail.gmail.com>
<CALj2ACUO6oz-43ryqfMOVZ_Q-N10C5tkzKku12+QV02NnXsDrw@mail.gmail.com>
<[email protected]>
On Thu, Sep 29, 2022 at 3:53 PM Bruce Momjian <[email protected]> wrote:
>
> So, what happens when an insufficient number of synchronous replicas
> reply?
It's a failover.
> Sessions hang because the synchronous behavior cannot be
> guaranteed. We then _allow_ query cancel so the user or administrator
> can get out of the hung sessions and perhaps modify
> synchronous_standby_names.
Administrators should not modify synchronous_standby_names.
Administrator must shoot this not in the head.
> I have always felt this has to be done at the server level, meaning when
> a synchronous_standby_names replica is not responding after a certain
> timeout, the administrator must be notified by calling a shell command
> defined in a GUC and all sessions will ignore the replica.
Standbys are expelled from the waitlist according to quorum rules. I'd
propose not to invent more quorum rules involving shell scripts.
The Administrator expressed what number of standbys can be offline by
setting synchronous_standby_names. They actively asked for hanging
queries in case of insufficient standbys.
We have reserved administrator connections for the case when all
connection slots are used by hanging queries.
Best regards, Andrey Borodin.
view thread (37+ messages) latest in thread
reply
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: [email protected]
Cc: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]
Subject: Re: An attempt to avoid locally-committed-but-not-replicated-to-standby-transactions in synchronous replication
In-Reply-To: <CAAhFRxjFGSk-hVTjnpFwm1XBUcHL8Obugt=P+ixV5AD9H+Kkrw@mail.gmail.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox