Re: Temporary tables and disk activity

Phil Endecott <spam_from_postgresql_general@chezphil.org> writes:
> Tom Lane wrote:
>> In principle, therefore, the kernel could hold temp table data in its
>> own disk buffers and never write it out to disk until the file is
>> deleted.  In practice, of course, the kernel doesn't know the data is
>> transient and will probably push it out whenever it has nothing else to
>> do.

> That makes sense.  I suspect that I am seeing writes every 5 seconds,
> which looks like bdflush / update.

> But my connections normally only last for a second at most.  In this
> case, surely the table would normally have been deleted before the
> kernel decided to write anything.

That does seem a bit odd, then.  Can you strace a typical backend
session and see if it's doing anything to force a disk write?

(I'm too lazy to go check right now whether 7.4 handled temp tables
exactly the same as CVS tip does.  I think it's the same but I might
be wrong.)

            regards, tom lane