In response to Ivan Voras : > A. Kretschmer wrote: > >In response to Tom : > >>I have a big table that is used for datalogging. I'm designing > >>graphing interface that will visualise the data. When the user is > >>looking at a small daterange I want the database to be queried for all > >>records, but when the user is 'zoomed out', looking at an overview, I > >>want run a query that skips every nth record and returns a managable > >>dataset that still gives a correct overview of the data without > >>slowing the programme down. Is there an easy way to do this that I > >>have overlooked? I looked at: > > > > > >Do you have 8.4? If yes: > > > >test=# create table data as select s as s from generate_Series(1,1000) s; > >SELECT > > > > > > > >test=*# select s from (select *, row_number() over (order by s) from > >data) foo where row_number % 3 = 0 limit 10; > > Won't this still read in the entire table and only then filter the > records out? Yes. But i think, the problem is the graphing interface. He wants anly a 'zoomed out' - overview, he needs a 'managable dataset'. Andreas -- Andreas Kretschmer Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header) GnuPG: 0x31720C99, 1006 CCB4 A326 1D42 6431 2EB0 389D 1DC2 3172 0C99 -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
