Date: Fri, 9 May 2014 09:53:36 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Gavin Flower <GavinFlower@archidevsys.co.nz>,
 "David E. Wheeler" <david@justatheory.com>,
 Greg Stark <stark@mit.edu>, Robert Haas <robertmhaas@gmail.com>,
 Heikki Linnakangas <hlinnakangas@vmware.com>,
 Andrew Dunstan <andrew@dunslane.net>, Peter Geoghegan <pg@heroku.com>,
 "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: default opclass for jsonb (was Re: Call for
 GIST/GIN/SP-GIST opclass documentation)
Message-ID: <20140509135336.GC23254@momjian.us>
References: <16769.1399407530@sss.pgh.pa.us>
 <20140506212020.GK30817@momjian.us>
 <57E8AA44-F816-45F2-BB61-5A854FFB0A97@justatheory.com>
 <28554.1399414853@sss.pgh.pa.us>
 <20140508134701.GO30817@momjian.us> <5819.1399558614@sss.pgh.pa.us>
 <1888.1399588751@sss.pgh.pa.us> <20140509033405.GA23254@momjian.us>
 <536C550F.50108@archidevsys.co.nz> <18360.1399633457@sss.pgh.pa.us>
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On Fri, May  9, 2014 at 07:04:17AM -0400, Tom Lane wrote:
> Gavin Flower <GavinFlower@archidevsys.co.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.

Should jsonb_hash_ops do only optional hashing too for long strings?

Also, with json_ops, when you index '{"exterior" : "white", "interior":
"blue"}', if you query for {"exterior" : "blue"}, does it match and have
to be rechecked in the heap because the index doesn't know which values
go with which keys?

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +


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