Re: failover vs. read only queries - Mailing list pgsql-hackers

From Fujii Masao
Subject Re: failover vs. read only queries
Date
Msg-id AANLkTikhQI9o3wmsloS00i0FiM2zJ4NIxz1BvwQGVEbT@mail.gmail.com
Whole thread Raw
In response to Re: failover vs. read only queries  (Takahiro Itagaki <itagaki.takahiro@oss.ntt.co.jp>)
Responses Re: failover vs. read only queries  (Takahiro Itagaki <itagaki.takahiro@oss.ntt.co.jp>)
List pgsql-hackers
On Wed, Jun 9, 2010 at 6:13 PM, Takahiro Itagaki
<itagaki.takahiro@oss.ntt.co.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


pgsql-hackers by date:

Previous
From: Fujii Masao
Date:
Subject: Re: failover vs. read only queries
Next
From: Mike Fowler
Date:
Subject: Adding XMLEXISTS to the grammar