Re: Returning the total number of rows as a separate column when using limit

"Gregory Stark" <stark(at)enterprisedb(dot)com> writes:

> "Andreas Joseph Krogh" <andreak(at)officenet(dot)no> writes:
>
>> That's what I'm doing now. I run the query with "limit+1" as limit and if it
>> results in more than limit, I know there is more data and I run count(*) to
>> count them all. But count(*) cannot use indices in PG so it's limited in
>> speed anyway AFAICS.
>
> Well count(*) can use indexes the same as the query can.
>
>> I really hoped there was an "Oracle over()" equivalent way in PG. I understand
>> that Oracle's LIMIT-hack with "3 subselects and rownum between 1 AND 20" is
>> rather expensive compared to PG's implementation of LIMIT. Oralce keeps
>> snapshot-info in the index, so counting only involves the index AFAIK.
>
> Well that's only going to be true if the index satisfies the whole query which
> is not going to be true for the simplest cases.

er, *except* for the simplest cases.

--
Gregory Stark
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