Re: 9.6 -> 10.0

On 5 April 2016 at 22:33, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Tue, Apr 5, 2016 at 10:25 AM, Simon Riggs <simon(at)2ndquadrant(dot)com>
> wrote:
> > On 22 March 2016 at 20:45, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> >>> While having parallelism is awesome, it's only going to affect a
> >>> (arguably small or big depending on your viewpoint) subset of users.
> It's
> >>> going to be massive for those users, but it's not going to be useful
> for
> >>> anywhere near as many users as streaming replication+hot
> standby+pg_upgrade
> >>> in 9.0, or pitr+windows in 8.0. And yes, the vacuum freeze thing is
> also
> >>> going to be great - for a small subset of users (yes, those users are
> in a
> >>> lot of pain now).
> >>
> >> We don't yet have full parallel query, we only have parallel scan and
> >> parallel aggregation.
> >
> > My comment here missed the point that parallel hash join is also now
> > possible for small hash tables, so we at least have a useful subset of
> > functionality across parallel scan/join/agg.
>
> Not sure if this matters to you, but nested loops with an inner index
> scan also work. The thing we don't support in parallel yet is merge
> joins.
>

I was aware, but there are no/few interesting queries where a nested loop
plan is the right choice that would also benefit from parallel query.

--
Simon Riggs http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
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