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Re: Limit allocated memory per session

From: Euler Taveira de Oliveira <euler(at)timbira(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, daveg <daveg(at)sonic(dot)net>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Limit allocated memory per session
Date: 2009-10-01 16:45:49
Message-ID: 4AC4DCBD.5030906@timbira.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Tom Lane escreveu:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> What WOULD be useful is to find a way to provide a way to configure
>> work_mem per backend rather than per executor node.  But that's a much
>> harder problem.
> 
> I think it's mostly a planner problem: how do you deal with the fact
> that that would make cost estimates for different sub-problems
> interrelated?  The cost of a hash, for instance, depends a lot on how
> much memory you assume it can use.
> 
It could introduce some complexity but you could track (subtract) the memory
usage as you're walking up the tree. Also, you need to decide what to do when
you have more than one node per level. :( How do you deal with priority in
this case?


-- 
  Euler Taveira de Oliveira
  http://www.timbira.com/

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