| From: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com> |
|---|---|
| To: | Markus Wanner <markus(at)bluegap(dot)ch> |
| Cc: | Dimitri Fontaine <dimitri(at)2ndquadrant(dot)fr>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Jeff Davis <pgsql(at)j-davis(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Issues with Quorum Commit |
| Date: | 2010-10-08 03:41:29 |
| Message-ID: | AANLkTi=f7TtF2=sKeHg+=E1puZmV=brtuUwMinPp9iNS@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Oct 7, 2010 at 3:01 AM, Markus Wanner <markus(at)bluegap(dot)ch> wrote:
> Of course, it doesn't make sense to wait-forever on *every* standby that
> ever gets added. Quorum commit is required, yes (and that's what this
> thread is about, IIRC). But with quorum commit, adding a standby only
> improves availability, but certainly doesn't block the master in any
> way.
But, even with quorum commit, if you choose wait-forever option,
failover would decrease availability. Right after the failover,
no standby has connected to new master, so if quorum >= 1, all
the transactions must wait for a while.
Basically we need to take a base backup from new master to start
the standbys and make them connect to new master. This might take
a long time. Since transaction commits cannot advance for that time,
availability would goes down.
Or you think that wait-forever option is applied only when the
standby goes down?
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
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