On Mon, Jun 12, 2017 at 8:17 PM, Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
> I know PG 10 will have support "CREATE STATISTICS.." for this..
>
> ..but I wondered if there's a recommended workaround in earlier versions ?
>
Not without seeing the query....
>
> 2) memory explosion in hash join (due to poor estimate?) caused OOM.
>
As far as I know, the only way a hash join should do this is if the join
includes a huge number of rows with exactly the same 32 bit hash codes.
Otherwise, it should spill to disk without causing OOM. Hash aggregates,
on the other hand, are a different matter.
Cheers,
Jeff