What does EXPLAIN QUERY PLAN says?

Il giorno 13 aprile 2012 21:04, Marc L. Allen
<mlal...@outsitenetworks.com>ha scritto:

> Maybe the query analyzer isn't smart enough to do two seeks in this case,
> so it does a scan?
>
> > -----Original Message-----
> > From: sqlite-users-boun...@sqlite.org [mailto:sqlite-users-
> > boun...@sqlite.org] On Behalf Of Steinar Midtskogen
> > Sent: Friday, April 13, 2012 3:00 PM
> > To: sqlite-users@sqlite.org
> > Subject: [sqlite] Why are two select statements 2000 times faster than
> > one?
> >
> > Hello,
> >
> > I have a table with "unix_time" as primary key and I want to get the
> > minimum and maximum values of "unix_time".  When I do:
> >
> >   SELECT min(unix_time), max(unix_time) from table;
> >
> > it is very slow.  It takes about 250ms, nearly everything in the
> > step() call.
> >
> > However, if I do:
> >
> >   SELECT min(unix_time) FROM table; SELECT max(unix_time) FROM table;
> >
> > to get the same values, it takes a fraction of the time.  The speedup
> > is more than 2000x.
> >
> > Why?
> >
> > --
> > Steinar
> > _______________________________________________
> > sqlite-users mailing list
> > sqlite-users@sqlite.org
> > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
> _______________________________________________
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