Re: failover vs. read only queries

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