Horton

Re: Standalone synchronous master

Bruce Momjian <bruce@momjian.us>

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From: Bruce Momjian <bruce@momjian.us>
To: Josh Berkus <josh@agliodbs.com>
Cc: Andres Freund <andres@2ndquadrant.com>, "Joshua D. Drake" <jd@commandprompt.com>, Amit Kapila <amit.kapila16@gmail.com>, Hannu Krosing <hannu@2ndquadrant.com>, MauMau <maumau307@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Kevin Grittner <kgrittn@ymail.com>, Heikki Linnakangas <hlinnakangas@vmware.com>, Simon Riggs <simon@2ndquadrant.com>, Rajeev rastogi <rajeev.rastogi@huawei.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2014-01-12T04:33:04Z
Lists: pgsql-hackers 
On Sat, Jan 11, 2014 at 07:18:02PM -0800, Josh Berkus wrote:
> In other words, if we're going to have auto-degrade, the most
> intelligent place for it is in
> RepMgr/HandyRep/OmniPITR/pgPoolII/whatever.  It's also the *easiest*
> place.  Anything we do *inside* Postgres is going to have a really,
> really hard time determining when to degrade.

Well, one goal I was considering is that if a commit is hung waiting for
slave sync confirmation, and the timeout happens, then the mode is
changed to degraded and the commit returns success.  I am not sure how
you would do that in an external tool, meaning there is going to be
period where commits fail, unless you think there is a way that when the
external tool changes the mode to degrade that all hung commits
complete.  That would be nice.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +