On Wed, Jul 11, 2012 at 7:49 PM, Kohji Nakamura <k.nakam...@nao.ac.jp>wrote:
> Hello all, > > I found that the access to an indexed column without "order by" is slower > than the one with "order by" in SQLite 3071300. > Using an index rather than an actual column is faster even if there is no > need to use the index when the column has index. > In general, to fetch column value, there is no need to access actual > column when it has a dedicated index or it is a first column of composite > index. > I hope SQLite would do this optimization which is common to other DBMSs. > > Followings are the results of the comparison. Time column of main table > has an index. > > After disk cache is cleared, > SQL: select time from main order by time; > Total : 38.1312 sec > > SQL: select time from main; > Total : 95.395 sec > Can you please send us the output of EXPLAIN QUERY PLAN for these two queries on your schema? > > When data is cached, > SQL: select time from main order by time; > Total : 0.497981 sec > > SQL: select time from main; > Total:: 0.925122 sec > > Thank you for developing a very cool DBMS, SQLite! > Kohji Nakamura > -- > k.nakam...@nao.ac.jp http://www.nao.ac.jp/E/index.html > National Astronomical Observatory of Japan > > > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
