| From: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com> |
|---|---|
| To: | Josh Berkus <josh(at)agliodbs(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: failover vs. read only queries |
| Date: | 2010-06-11 02:26:30 |
| Message-ID: | AANLkTino18rDhE3NJQVMz7C-hhKM0NfH7fJ2oSo9jxAS@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Jun 11, 2010 at 1:48 AM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
> On 06/09/2010 07:36 PM, Mark Kirkwood wrote:
>>
>> On 10/06/10 14:07, Tatsuo Ishii wrote:
>>>
>>> The one of top 3 questions I got
>>> when we propose them our HA solution is, "how long will it take to
>>> do failover when the master DB crashes?"
>>>
>>
>> Same here +1
>
> In that case, wouldn't they set max_standby_delay to 0? In which case the
> failover problem goes away, no?
Yes, but I guess they'd also like to run read only queries on the standby.
Setting max_standby_delay to 0 would prevent them from doing that because
the conflict with the replay of the VACUUM or HOT record would often happen.
vacuum_defer_cleanup_age would be helpful for that case, but it seems to be
hard to tune that.
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
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