Re: Call for GIST/GIN/SP-GIST opclass documentation

On Tue, Apr 8, 2014 at 1:41 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I just created sections in the SGML manual chapters about GIST, GIN, and
> SP-GIST to hold documentation about the standard opclasses provided for
> them:

I think that that's a good idea. I too was bothered by this omission.

> Of the two operator classes for type jsonb, jsonb_ops is the
> default. jsonb_hash_ops supports fewer operators but will work with
> larger indexed values than jsonb_ops can support.
>
> Is that accurate? Do we need to say more?

Well, I'm not sure that it's worth noting there, but as you probably
already know jsonb_hash_ops will perform a lot better than the default
GIN opclass, and will have much smaller indexes. FWIW I think that the
size limitation is overblown, and performance is in fact the
compelling reason to prefer jsonb_hash_ops, although it's probably
incongruous to explain the issues that way in this section of the
docs. It probably suffices that that is covered in the "JSON Types"
section.

--
Peter Geoghegan