On Monday 05 November 2007 15:18:22 Tom Lane wrote:
> Andreas Joseph Krogh <andreak@officenet.no> writes:
> > AFAICS the information about the *total* number of rows is in the
> > "result" somehow. When I execute a "limit 1" query with EXPLAIN ANALYZE,
> > I se the total number of columns in "rows=200819", so the information is
> > there.
>
> That's only an estimate. Since the query doesn't get executed to
> completion thanks to the LIMIT, Postgres really has no idea whether
> the estimate is accurate.
Ok. The query is ORDER-ed, but you're saying that it doesn't matter and PG
still doesn't have to know the total numbers even if it has to sort the
result?
Is there a way to perform the LIMIT-query only once and still be able to
extract the total number of rows from some "magic function", like
Oracle's "over()" analytic function? I will accept a simple "no" if that is
the case, but if it is possible (like it is in Oracle) I would appreciate to
know how to do it.
--
Andreas Joseph Krogh <andreak@officenet.no>
Senior Software Developer / Manager
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