Thread: Odd behavior with temp usage logging

Folks,

I turned on temp file logging for PostgreSQL to see if I needed to
adjust work_mem.  Oddly, it's logging file usage up to 33 times per
executed query (and no, the query isn't large enough to need 33 separate
sorts).

Any idea what's going on here?

--Josh

Josh Berkus wrote:
> Folks,
>
> I turned on temp file logging for PostgreSQL to see if I needed to
> adjust work_mem.  Oddly, it's logging file usage up to 33 times per
> executed query (and no, the query isn't large enough to need 33 separate
> sorts).

Are you sure there's not a sort happening inside a loop? It might help
if you posted the actual log messages along with the output of `EXPLAIN
ANALYZE' on your query.

--
Craig Ringer

Craig Ringer wrote:
> Josh Berkus wrote:
>> Folks,
>>
>> I turned on temp file logging for PostgreSQL to see if I needed to
>> adjust work_mem.  Oddly, it's logging file usage up to 33 times per
>> executed query (and no, the query isn't large enough to need 33 separate
>> sorts).
>
> Are you sure there's not a sort happening inside a loop? It might help
> if you posted the actual log messages along with the output of `EXPLAIN
> ANALYZE' on your query.

Hmmm, it's possible.  The sort sizes seem very large for the query in
question, though.  Will have to check when I get back on the system.

That would make a TODO in tempfile logging though ... it would be *far*
more useful to colect summary stats per query than log each individual sort.

--Josh