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Re: Hot Standby query cancellation and Streaming Replication integration

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Dimitri Fontaine <dfontaine(at)hi-media(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Greg Stark <gsstark(at)mit(dot)edu>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Hot Standby query cancellation and Streaming Replication integration
Date: 2010-02-26 21:48:38
Message-ID: 201002262148.o1QLmch23807@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Dimitri Fontaine wrote:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> > Well, as Heikki said, a stop-and-go WAL management approach could deal
> > with that use-case.  What I'm concerned about here is the complexity,
> > reliability, maintainability of trying to interlock WAL application with
> > slave queries in any sort of fine-grained fashion.
> 
> Some admin functions for Hot Standby were removed from the path to ease
> its integration, there was a pause() and resume() feature.
> 
> I think that offering this explicit control to the user would allow them
> to choose between HA setup and reporting setup easily enough: just pause
> the replay when running the reporting, resume it to get fresh data
> again. If you don't pause, any query can get killed, replay is the
> priority.

Doesn't the system already adjust the delay based on the length of slave
transactions, e.g. max_standby_delay.  It seems there is no need for a
user switch --- just max_standby_delay really high.

-- 
  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: A thought on Index Organized Tables
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Subject: Re: Hot Standby query cancellation and Streaming Replication integration

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