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Re: Re: Hot Standby query cancellation and Streaming Replication integration

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Greg Stark <gsstark(at)mit(dot)edu>, Greg Smith <greg(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Re: Hot Standby query cancellation and Streaming Replication integration
Date: 2010-02-26 19:01:30
Message-ID: 201002261901.o1QJ1UY04265@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Tom Lane wrote:
> I'm going to make an unvarnished assertion here.  I believe that the
> notion of synchronizing the WAL stream against slave queries is
> fundamentally wrong and we will never be able to make it work.
> The information needed isn't available in the log stream and can't be
> made available without very large additions (and consequent performance
> penalties).  As we start getting actual beta testing we are going to
> uncover all sorts of missed cases that are not going to be fixable
> without piling additional ugly kluges on top of the ones Simon has
> already crammed into the system.  Performance and reliability will both
> suffer.
> 
> I think that what we are going to have to do before we can ship 9.0
> is rip all of that stuff out and replace it with the sort of closed-loop
> synchronization Greg Smith is pushing.  It will probably be several
> months before everyone is forced to accept that, which is why 9.0 is
> not going to ship this year.

Wow, can I have some varnish with that.  :-O

You are right that we need to go down the road a bit before we know what
we need for 9.0 or 9.1.

-- 
  Bruce Momjian  <bruce(at)momjian(dot)us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com
  PG East:  http://www.enterprisedb.com/community/nav-pg-east-2010.do
  + If your life is a hard drive, Christ can be your backup. +

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Subject: Re: Hot Standby query cancellation and Streaming Replication integration
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