Skip site navigation (1) Skip section navigation (2)

Re: Re: Hot Standby query cancellation and StreamingReplication integration

From: Aidan Van Dyk <aidan(at)highrise(dot)ca>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Greg Stark <stark(at)mit(dot)edu>, Josh Berkus <josh(at)agliodbs(dot)com>,PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>,Greg Smith <greg(at)2ndquadrant(dot)com>,Robert Haas <robertmhaas(at)gmail(dot)com>
Subject: Re: Re: Hot Standby query cancellation and StreamingReplication integration
Date: 2010-03-02 02:08:27
Message-ID: 20100302020827.GF10960@oak.highrise.ca (view raw or flat)
Thread:
Lists: pgsql-hackers
* Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> [100301 20:04]:
> Greg Stark <stark(at)mit(dot)edu> writes:
> > josh, nobody is talking about it because it doesn't make sense. you could
> > only retry if it was the first query in the transaction and only if you
> > could prove there were no side-effects outside the database and then you
> > would have no reason to think the retry would be any more likely to work.
> 
> But it's hot standby, so there are no data-modifying transactions.
> Volatile functions could be a problem, though.  A bigger problem is
> we might have already shipped partial query results to the client.

But, since we know its a slave and that the reason the query was
cancelled was because it's got a backlog of updates to apply, it's very
likely that the data that the earlier parts of the transaction would be
different...

And then you have no idea if just blindly replaying all statements of
the transaction successively is a good idea...


a.

-- 
Aidan Van Dyk                                             Create like a god,
aidan(at)highrise(dot)ca                                       command like a king,
http://www.highrise.ca/                                   work like a slave.

In response to

pgsql-hackers by date

Next:From: Bruce MomjianDate: 2010-03-02 03:36:44
Subject: Re: [GENERAL] trouble with to_char('L')
Previous:From: Robert HaasDate: 2010-03-02 01:50:28
Subject: Re: Re: Hot Standby query cancellation and Streaming Replication integration

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group