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

Peter Geoghegan <pg(at)heroku(dot)com> writes:
> On Tue, Apr 8, 2014 at 1:41 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> 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.

Well, the subtext is whether we should move that discussion to this
new section. I think there is some comparable discussion in the
full-text-indexing chapter, too.

(BTW, wasn't there some discussion of changing our minds about which
one is the default? We already have one bug report complaining about
jsonb_ops' size restriction, so that seems to be evidence in favor
of changing ...)

regards, tom lane