Re: hashjoins vs. Bloom filters (yet again)

On Wed, Aug 19, 2026 at 10:32:19PM +0200, Tomas Vondra wrote:
> On 8/19/26 21:25, Bruce Momjian wrote:
> > Yeah, not sure what I am asking. It was just a thought that maybe more
> > flexible index combining can be helpful.
> >
>
> I agree, but I think it's mostly orthogonal to what this thread is
> about. I mean, maybe the plan below Hash would benefit from a scan
> combining indexes like this, but for the filter (built "on" the
> hashtable) that's transparent.
>
> We could also push the filters to this scan node, but then it's not
> different from other scans. Although, it may not be entirely clear to
> which of the scans to push it - but I realize we may already have that
> issue with the Bitmap Heap Scan / Bitmap Index Scan.
>
> So I still think it's a mostly independent feature.

I mentioned it because you listed various filtering types:

> * Bloom filters
> * exact "IN" list of values
> * min/max range filter

and I was asking if these can be efficitntly combined today, but you are
right it is a later discussion. The Pittsburgh discussion was related
to how k-NN/nearest-neighbor vector searches could be combined with
other index lookups.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

Do not let urgent matters crowd out time for investment in the future.