From: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com> |
---|---|
To: | Takahiro Itagaki <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: failover vs. read only queries |
Date: | 2010-06-09 09:49:19 |
Message-ID: | AANLkTikhQI9o3wmsloS00i0FiM2zJ4NIxz1BvwQGVEbT@mail.gmail.com |
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Lists: | pgsql-hackers |
On Wed, Jun 9, 2010 at 6:13 PM, Takahiro Itagaki
<itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> wrote:
>> To fix the problem, when the trigger file is found, I think
>> that we should cancel all the running read only queries
>> immediately (or forcibly use -1 as the max_standby_delay
>> since that point) and make the recovery go ahead.
>
> Hmmm, does the following sequence work as your expect instead of the chanage?
> It requires text-file manipulation in 1, but seems to be more flexible.
>
> 1. Reset max_standby_delay = 0 in postgresql.conf
> 2. pg_ctl reload
> 3. Create a trigger file
As far as I read the HS code, SIGHUP is not checked while a recovery
is waiting for queries :( So pg_ctl reload would have no effect on
the conflicting queries.
Independently from the problem I raised, I think that we should call
HandleStartupProcInterrupts() in that sleep loop.
> BTW, I hope we will have "pg_ctl failover --timeout=N" in 9.1
> instead of the trigger file based management.
Please feel free to try that ;)
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
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