From: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com> |
---|---|
To: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> |
Cc: | Stephen Frost <sfrost(at)snowman(dot)net>, Robert Haas <robertmhaas(at)gmail(dot)com>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Ryan Murphy <ryanfmurphy(at)gmail(dot)com>, Beena Emerson <memissemerson(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Re: Clarifying "server starting" messaging in pg_ctl start without --wait |
Date: | 2017-01-18 23:54:56 |
Message-ID: | CAB7nPqR08Cpu5JraVtWAqQPfPoxbS2kdzCu-DTxSaV5bEkONOA@mail.gmail.com |
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On Thu, Jan 19, 2017 at 5:01 AM, Peter Eisentraut
<peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote:
> On 1/18/17 8:25 AM, Stephen Frost wrote:
>> I was actually thinking about it the other way- start out by changing
>> them to both be 5m and then document next to checkpoint_timeout (and
>> max_wal_size, perhaps...) that if you go changing those parameters (eg:
>> bumping up checkpoint_timeout to 30 minutes and max_wal_size up enough
>> that you're still checkpointing based on time and not due to running out
>> of WAL space) then you might need to consider raising the timeout for
>> pg_ctl to wait around for the server to finish going through crash
>> recovery due to all of the outstanding changes since the last
>> checkpoint.
>
> It is important for users to be aware of this, but I don't think the
> relationship between checkpoint_timeout and recovery time is linear, so
> it's unclear what the exact advice should be.
This is a right assumption for steady workloads with few DDLs, but for
example once a couple of CREATE DATABASE records are in such a law is
broken.
--
Michael
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