Re: returning only part of a rule set

Adrian Klaver-4 wrote
>>
>> If I am only interested in get 2 entries per result set,  I would expect
>> to see
>
> Actually <=2.
> How do you determine which rows to keep, by id or something else?
>
>>
>> 1 xx,yy
>> 2 xx,yy
>>
>>
>> 1,dd,zz
>> 2,dd,zz
>>
>> 1, ee,ff
>>
>> Using LIMIT only gives
>> 1 xx,yy
>> 2 xx,yy
>>
>> Sorry for not explaining it very,  I want to limit the size of an
>> inviduail set of records which is part of set of records.
>
> It would help if we could see the actual query you are using to get the
> result sets, suitably anonymized if needed.

The general answer is that you use a window clause and a row_number()
function over an appropriate partiton.  Put that in a subquery then in the
outer query add a where clause for row_number <= 2.

David J.






--
View this message in context: http://postgresql.nabble.com/returning-only-part-of-a-rule-set-tp5828217p5828226.html
Sent from the PostgreSQL - general mailing list archive at Nabble.com.