Re: GIN improvements part2: fast scan

From: Alexander Korotkov <aekorotkov(at)gmail(dot)com>
To: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>
Cc: Tomas Vondra <tv(at)fuzzy(dot)cz>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: GIN improvements part2: fast scan
Date: 2014-03-13 18:10:27
Message-ID: CAPpHfduVwSF4f9poxQ1DXhdsoqtFCNpy7AbdpXgkdifL_Yrs-A@mail.gmail.com
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On Thu, Mar 13, 2014 at 8:58 PM, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com
> wrote:

> On 03/12/2014 07:52 PM, Alexander Korotkov wrote:
>
>> >
>>> >* I just noticed that the dummy trueTriConsistentFn returns GIN_MAYBE,
>>> >rather than GIN_TRUE. The equivalent boolean version returns 'true'
>>> without
>>> >recheck. Is that a typo, or was there some reason for the discrepancy?
>>> >
>>>
>> Actually, there is not difference in current implementation, But I
>> implemented it so that trueTriConsistentFn can correctly work
>> with shimBoolConsistentFn. In this case it should return GIN_MAYBE in case
>> when it have no GIN_MAYBE in the input (as analogue of setting recheck
>> flag). So, it could return GIN_TRUE only if it checked that input has
>> GIN_MAYBE. However, checking would be just wasting of cycles. So I end up
>> with just GIN_MAYBE :-)
>>
>
> I don't understand that. As it is, it's inconsistent with the boolean
> trueConsistent function. trueConsistent always returns TRUE with
> recheck=false. And in GIN_SEARCH_MODE_EVERYTHING mode, there are no regular
> scan keys.

Ok, I see. I just messed it up.

------
With best regards,
Alexander Korotkov.

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