Re: GIN improvements part2: fast scan

On Sun, Jan 26, 2014 at 8:14 PM, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com
> wrote:

> In addition to that, I'm using the ternary consistent function to check
>> if minItem is a match, even if we haven't loaded all the entries yet.
>> That's less important, but I think for something like "rare1 | (rare2 &
>> frequent)" it might be useful. It would allow us to skip fetching
>> 'frequent', when we already know that 'rare1' matches for the current
>> item. I'm not sure if that's worth the cycles, but it seemed like an
>> obvious thing to do, now that we have the ternary consistent function.
>>
>
> So, that clearly isn't worth the cycles :-). At least not with an
> expensive consistent function; it might be worthwhile if we pre-build the
> truth-table, or cache the results of the consistent function.
>

I believe cache consistent function results is quite same as lazy
truth-table. I think it's a good option to use with two-state consistent
function. However, I don't think it's a reason to refuse from three-state
consistent function because number of entries could be large.

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