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

On 2014-05-09 10:26:48 -0400, Bruce Momjian wrote:
> 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@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.
> 
> 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?

The operator class has to be specified after the USING GIN in CREATE
INDEX so I think that rest is neglegible.

Greetings,

Andres Freund

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