This is my query: select phn,random() as ran from demographics where sex='F' and dob >= 19400401 and dob <=19450331 order by ran limit 500 The original table has 7 million records and I am trying to select a subset of about 40000 and sort them in random order. I am doing this to get a random 500 records.
On Thu, May 8, 2008 at 9:17 AM, John Stanton <[EMAIL PROTECTED]> wrote: > Dennis Cote wrote: > > Barbara Weinberg wrote: > >> I was wondering whether anyone had tried sorting records in random > order > >> using sqlite3. I tried sorting by random() and randomblob() but it was > very > >> slow and chewed up lots of resources. Any suggestions? > > > > Can you provide any more details about what you are trying to > accomplish? > > > > There have been several previous discussions about selecting random > > records from a table. You may want to look for those in the archives. If > > you really need to sort the entire table then you are probably stuck > > with the slow operation. If you only need a random subset of a table > > then you may be able to use some of these ideas to speed things up. > > > > HTH > > Dennis Cote > > > > If you have sequential rowids and know the largest then you can use a PRNG > and get a random rowid to lookup. That will be optimally fast. > > _______________________________________________ > sqlite-users mailing list > [email protected] > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list [email protected] http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
