Florian Weimer <fweimer(at)redhat(dot)com> writes:
> I've got a query which causes PostgreSQL to create hundreds of thousands
> of temporary files, many of them empty. The process also needs a lot of
> memory. I suspect this is due to bookkeeping for those files.
> The query looks like this:
> [ huge hash join ]
> I track this down to a lower-than-usual setting of work_mem, to 1MB,
> after the upgrade to 9.3.
The system is trying to do the join with only 1MB of workspace, so
yes, you end up with lots and lots of small temporary files.
> Is this a bug?
No.
regards, tom lane