Re: Improving executor performance - tidbitmap

On 2016-07-17 08:32:17 -0400, Robert Haas wrote:
> On Wed, Jul 13, 2016 at 11:06 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> > The major issue with the simplehash implementation in the path is
> > probably the deletion; which should rather move cells around, rather
> > than use toombstones. But that was too complex for a POC ;). Also, it'd
> > likely need a proper iterator interface.
>
> Do we ever need to delete from a TIDBitmap? Probably not, but I'm
> guessing you have other uses for this in mind.

We do, via BitmapAnd.

> > FWIW, the dynahash usage in nodeAgg.c is a major bottleneck in a number
> > of other queries.
>
> Can we use this implementation for that as well, or are we going to
> need yet another one?

I've not tested it, but I'd assume that something like the simplehash
should work there. It's a bit more complicated of a scenario though.

Andres