"Atul Deopujari" <[EMAIL PROTECTED]> writes:
> Hi,
> Tom Lane wrote:
>> That's the least of the problems. We really ought to convert such cases
>> into an IN (VALUES(...)) type of query, since often repeated indexscans
>> aren't the best implementation.
>>
> I thought of giving this a shot and while I was working on it, it
> occurred to me that we need to decide on a threshold value of the IN
> list size above which such transformation should take place.
I see no good reason to suppose that there is/should be a constant
threshold --- most likely it depends on size of table, availability of
indexes, etc. Having the planner try it both ways and compare costs
would be best.
regards, tom lane
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