Re: File leak?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: File leak?
Date: 2004-06-14 12:42:46
Message-ID: 26133.1087216966@sss.pgh.pa.us
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Heikki Linnakangas <hlinnaka(at)iki(dot)fi> writes:
> I'm afraid that's not enough. Checkpoints spoil it, think:

> 1. CREATE TABLE foobar ...
> 2. INSERT ....
> 3. <checkpoint>
> 4. <crash>

> The replay would not see the file-creation WAL record.

Good point. That makes it messy enough that we probably don't want to
do it that way. Scan-for-unreferenced-files is looking a lot more
robust (although it has its own interesting race-condition issues if
you try to do it in a live system).

>> I'm not sure what the performance implications of this would be; it's
>> likely that pushing the cost somewhere else would be better.

> I don't think that file creation is that common for it to matter..

Maybe not for regular tables, but for temp tables I'm less convinced.
If we could do the unreferenced-file scan only at completion of a crash
recovery then it'd be zero cost in all normal paths ...

regards, tom lane

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