Re: [v9.5] Custom Plan API

* Simon Riggs (simon@2ndQuadrant.com) wrote:
> IMHO we would not want to add indexes to every column, on every table,
> nor would we wish to use lookaside for all tables. It is a good thing
> to be able to add optimizations for individual tables. GPUs are not
> good for everything; it is good to be able to leverage their
> strengths, yet avoid their weaknesses.

It's the optimizer's job to figure out which path to pick though, based
on which will have the lowest cost.

> If do you want that, you can write an Event Trigger that automatically
> adds a lookaside for any table.

This sounds terribly ugly and like we're pushing optimization decisions
on to the user instead of just figuring out what the best answer is.

> I agree TupleTableSlot may not be best way for bulk data movement. We
> probably need to look at buffering/bulk movement between executor
> nodes in general, which would be of benefit for the FDW case also.
> This would be a problem even for Custom Scans as originally presented
> also, so I don't see much change there.

Being able to do bulk movement would be useful, but (as I proposed
months ago) being able to do asyncronous returns would be extremely
useful also, when you consider FDWs and Append()- the main point there
being that you want to keep the FDWs busy and working in parallel.
Thanks,
    Stephen