Re: Re: patch review : Add ability to constrain backend temporary file space

From: Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz>
To: Cédric Villemain <cedric(dot)villemain(dot)debian(at)gmail(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Re: patch review : Add ability to constrain backend temporary file space
Date: 2011-06-21 23:13:12
Message-ID: 4E012588.5030106@catalyst.net.nz
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On 21/06/11 02:39, Cédric Villemain wrote:
> 2011/6/20 Robert Haas<robertmhaas(at)gmail(dot)com>:
>> On Mon, Jun 20, 2011 at 9:15 AM, Cédric Villemain
>> <cedric(dot)villemain(dot)debian(at)gmail(dot)com> wrote:
>>> The feature does not work exactly as expected because the write limit
>>> is rounded per 8kB because we write before checking. I believe if one
>>> write a file of 1GB in one pass (instead of repetitive 8kB increment),
>>> and the temp_file_limit is 0, then the server will write the 1GB
>>> before aborting.
>> Can we rearrange thing so we check first, and then write?
> probably but it needs more work to catch corner cases. We may be safe
> to just document that (and also in the code). The only way I see so
> far to have a larger value than 8kB here is to have a plugin doing the
> sort instead of the postgresql core sort algo.
>
>

Thanks guys - will look at moving the check, and adding some
documentation about the possible impacts of plugins (or new executor
methods) that might write in chunks bigger than blocksz.

Maybe a few days - I'm home sick ATM, plus looking after these
http://www.maftet.co.nz/kittens.html

Cheers

Mark

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