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From: Gavin Flower <[email protected]>
To: Bruce Momjian <[email protected]>
To: Tom Lane <[email protected]>
Cc: David E. Wheeler <[email protected]>
Cc: Greg Stark <[email protected]>
Cc: Robert Haas <[email protected]>
Cc: Heikki Linnakangas <[email protected]>
Cc: Andrew Dunstan <[email protected]>
Cc: Peter Geoghegan <[email protected]>
Cc: [email protected] <[email protected]>
Subject: Re: default opclass for jsonb (was Re: Call for GIST/GIN/SP-GIST opclass documentation)
Date: Fri, 09 May 2014 16:09:51 +1200
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
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On 09/05/14 15:34, Bruce Momjian wrote:
> On Thu, May  8, 2014 at 06:39:11PM -0400, Tom Lane wrote:
>> I wrote:
>>> I think the idea of hashing only keys/values that are "too long" is a
>>> reasonable compromise.  I've not finished coding it (because I keep
>>> getting distracted by other problems in the code :-() but it does not
>>> look to be very difficult.  I'm envisioning the cutoff as being something
>>> like 128 bytes; in practice that would mean that few if any keys get
>>> hashed, I think.
>> Attached is a draft patch for this.  In addition to the hash logic per se,
>> I made these changes:
>>
>> * Replaced the K/V prefix bytes with a code that distinguishes the types
>> of JSON values.  While this is not of any huge significance for the
>> current index search operators, it's basically free to store the info,
>> so I think we should do it for possible future use.
>>
>> * Fixed the problem with "exists" returning rows it shouldn't.  I
>> concluded that the best fix is just to force recheck for exists, which
>> allows considerable simplification in the consistent functions.
>>
>> * Tried to improve the comments in jsonb_gin.c.
>>
>> Barring objections I'll commit this tomorrow, and also try to improve the
>> user-facing documentation about the jsonb opclasses.
> 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.


Cheers,
Gavin



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