Re: asynchronous and vectorized execution

On Tue, May 10, 2016 at 3:42 PM, Konstantin Knizhnik
<k.knizhnik@postgrespro.ru> wrote:
> Doesn't this actually mean that we need to have normal job scheduler which
> is given queue of jobs and having some pool of threads will be able to
> orginize efficient execution of queries? Optimizer can build pipeline
> (graph) of tasks, which corresponds to execution plan nodes, i.e. SeqScan,
> Sort, ... Each task is splitted into several jobs which can be concurretly
> scheduled by task dispatcher.  So you will not have blocked worker waiting
> for something and all system resources will be utilized. Such approach with
> dispatcher allows to implement quotas, priorities,... Also dispatches can
> care about NUMA and cache optimizations which is especially critical on
> modern architectures. One more reference:
> http://db.in.tum.de/~leis/papers/morsels.pdf

I read this as a proposal to redesign the entire optimizer and
executor to use some new kind of plan.  That's not a project I'm
willing to entertain; it is hard to imagine we could do it in a
reasonable period of time without introducing bugs and performance
regressions.  I think there is a great deal of performance benefit
that we can get by changing things incrementally.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company