Re: default opclass for jsonb (was Re: Call for GIST/GIN/SP-GIST opclass documentation)

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz>, "David E(dot) Wheeler" <david(at)justatheory(dot)com>, Greg Stark <stark(at)mit(dot)edu>, Robert Haas <robertmhaas(at)gmail(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Peter Geoghegan <pg(at)heroku(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: default opclass for jsonb (was Re: Call for GIST/GIN/SP-GIST opclass documentation)
Date: 2014-05-09 14:26:48
Message-ID: 20140509142648.GD23254@momjian.us
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On Fri, May 9, 2014 at 09:53:36AM -0400, Bruce Momjian wrote:
> On Fri, May 9, 2014 at 07:04:17AM -0400, Tom Lane wrote:
> > Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz> writes:
> > > On 09/05/14 15:34, Bruce Momjian wrote:
> > >> Looks good. I was thinking the jsonb_ops name could remain unchanged
> > >> and the jsonb_hash_ops could be called jsonb_combo_ops as it combines
> > >> the key and value into a single index entry.
> >
> > > If you have 'jsonb_combo_ops' - then surely 'jsonb_op' should be called
> > > 'jsonb_xxx_ops', where the 'xxx' distinguishes that from
> > > 'jsonb_combo_ops'? I guess, if any appropriate wording of 'xxx' was too
> > > cumbersome, then it would be worse.
> >
> > Yeah, I'm disinclined to change the opclass names now. It's not apparent
> > to me that "combo" is a better choice than "hash" for the second opclass.
>
> Well, if we are optionally hashing json_ops for long strings, what does
> jsonb_hash_ops do uniquely with hashing? Does it always hash, while
> json_ops optionally hashes? Is that the distinguishing characteristic?
> It seemed the _content_ of the indexed value was more important, rather
> than the storage method.

Also, are people going to think that jsonb_hash_ops creates a hash
index, which is not crash safe, even though it is a GIN index? Do we
have this "hash" confusion anywhere else?

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

+ Everyone has their own god. +

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