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From: Andrew Dunstan <[email protected]>
To: Peter Geoghegan <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: [email protected]
Subject: Re: default opclass for jsonb (was Re: Call for GIST/GIN/SP-GIST opclass documentation)
Date: Tue, 08 Apr 2014 18:18:31 -0400
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On 04/08/2014 05:57 PM, Peter Geoghegan wrote:
> On Tue, Apr 8, 2014 at 2:46 PM, Tom Lane <[email protected]> wrote:
>> Well, let me see if I understand the situation correctly:
>>
>> * jsonb_ops supports more operators
>>
>> * jsonb_hash_ops produces smaller, better-performing indexes
>>
>> * jsonb_ops falls over on inputs with wide field values, but
>> jsonb_hash_ops does not
> There might be some compelling cases for indexing existence rather
> than containment, since the recheck flag isn't set there, but in
> general this summary seems sound. I would say that broadly, existence
> is a less useful operator than containment, and so jsonb_hash_ops is
> broadly more compelling. I didn't propose changing the default due to
> concerns about the POLA, but I'm happy to be told that those concerns
> were out of proportion to the practical benefits of a different
> default.
>


I tend to agree with Tom that POLA will be more violated by the default 
ops class not being able to index some values.

cheers

andrew


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