I've done the upgrade to 9.5. Memory bloat has reduced to a more manageable level. Most workers have an overhead of <20MB, with one outlier consuming 60MB.
— Theron On Fri, Aug 26, 2016 at 5:41 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Theron Luhn <the...@luhn.com> writes: > > Okay, I got a semi-reproducible test case: > > https://gist.github.com/luhn/2b35a9b31255e3a6a2e6a06d1213dfc9 > > > The one caveat is that the memory rise only happens when using a > > HashAggregate query plan (included in the gist), which I can't find a way > > to get Postgres to reliably use. > > OK, I can reproduce some memory bloat in 9.3, but not in 9.5 and up. > I believe this was fixed by commit b419865a8, which reduced the overhead > of running a lot of instances of array_agg() concurrently in a HashAgg > plan. I think your options are to live with it or upgrade. Or I guess > you could turn off enable_hashagg when using array_agg() plus GROUP BY, > though you'd want to remember to undo that whenever you do upgrade. > > regards, tom lane >
