Re: [postgis-users] Query with LIMIT but as random result set?
От | Stefan Keller |
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Тема | Re: [postgis-users] Query with LIMIT but as random result set? |
Дата | |
Msg-id | CAFcOn29BGASSaLtaoiaMPwn_SO_JdXc6xu9RW9irUe-tdKZK7w@mail.gmail.com обсуждение исходный текст |
Ответ на | Query with LIMIT but as random result set? (Stefan Keller <sfkeller@gmail.com>) |
Список | pgsql-general |
Hi, Thanks a lot to Adrian, Nicolas and Brooks. "... ORDER BY random() LIMIT 10;" works ok. But with the following option it gets more tricky assume: > And as an option the (limited) resultset should be spatially > distributed (not clustered). I'm thinking about some radial spatial distribution function. Yours, Stefan 2013/1/8 Brooks Kehler <brookskehler@gmail.com>: > this should work - > > order by random() limit 10; > > > > On Tue, Jan 8, 2013 at 10:20 AM, Stefan Keller <sfkeller@gmail.com> wrote: >> >> Hi >> >> I have a query like this >> >> SELECT ST_AsText(way) geom, name AS label >> FROM osm_point >> LIMIT 10; >> >> When I repeatedly do this, the result set will be always the same. >> I have observed this only empirically and I know that the ordering of >> the result set is undefined without ORDER BY. >> There are two indexes involved, one geospatial for way and one for name. >> >> My question is: Does someone have an idea on how to randomize the >> result set on every consecutive query? >> And as an option the (limited) resultset should be spatially >> distributed (not clustered). >> >> Yours, Stefan >> _______________________________________________ >> postgis-users mailing list >> postgis-users@lists.osgeo.org >> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > > > > _______________________________________________ > postgis-users mailing list > postgis-users@lists.osgeo.org > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >
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