On Tue, Apr 5, 2016 at 10:25 AM, Simon Riggs <simon@2ndquadrant.com> wrote: > On 22 March 2016 at 20:45, Simon Riggs <simon@2ndquadrant.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.
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Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
