Re: Next Steps with Hash Indexes

On Wed, Aug 11, 2021 at 8:47 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> > I have to admit that after working with Amit on all the work to make
> > hash indexes WAL-logged a few years ago, I was somewhat disillusioned
> > with the whole AM. It seems like a cool idea to me but it's just not
> > that well-implemented.
>
> Yeah, agreed. The whole buckets-are-integral-numbers-of-pages scheme
> is pretty well designed to ensure bloat, but trying to ameliorate that
> by reducing the number of buckets creates its own problems (since, as
> you mention, we have no scheme whatever for searching within a bucket).
> I'm quite unimpressed with Simon's upthread proposal to turn off bucket
> splitting without doing anything about the latter issue.
>

The design of the patch has changed since the initial proposal. It
tries to perform unique inserts by holding a write lock on the bucket
page to avoid duplicate inserts.

--
With Regards,
Amit Kapila.