Hmm. I was more interested in using COUNT( * ) than DISTINCT *.
I want a count of all rows, but I want to be able to specify which columns are distinct.
That's definitely an interesting approach, but testing doesn't show it to be appreciably faster.
If I do a DISTINCT *, postgres will attempt to guarantee that there are no duplicate values across all columns rather than a subset of columns? Is that right?
Anyway, I was just wondering if there were any best practices out there for counting distinct values in sets of values that might not themselves be distinct.
Thanks for the tips so far!
-tfo
-- Thomas F. O'Connell Co-Founder, Information Architect Sitening, LLC http://www.sitening.com/ 110 30th Avenue North, Suite 6 Nashville, TN 37203-6320 615-260-0005
On Nov 16, 2004, at 4:34 PM, Stephan Szabo wrote:
On Tue, 16 Nov 2004, Thomas F.O'Connell wrote:
Is there another way to accomplish what the former is doing, then?
The only thing I can think of is a subselect in from that uses distinct.
select count(*) from (select distinct ...) foo
That also theoretically allows you to use select distinct * inside the subselect.
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