Thanks again Clemens. > -----Original Message----- > From: [email protected] [mailto:sqlite-users- > [email protected]] On Behalf Of Clemens Ladisch > Sent: 09 November 2012 15:08 > To: [email protected] > Subject: Re: [sqlite] Anomalously slow performance on updates to > earlyentries in a DB > > O'Toole, Eamonn wrote: > > DELETE FROM object > > WHERE name = ? AND (created_at < ?) > > This needs an index with "name" as the *first* column. > > > query += ' AND deleted IN (0, 1)' > > If the name column is (nearly) unique, putting indexes on the > created_at > or deleted columns is not useful (for this query).
[O'Toole, Eamonn] The name column is guaranteed to be unique. > > See <http://www.sqlite.org/queryplanner.html> for an explanation of how > indexes work. > > > Regards, > Clemens > _______________________________________________ > 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
