On Wed, 9 May 2007 14:24:27 +0400 Tomash Brechko <[EMAIL PROTECTED]> wrote:
> On Wed, May 09, 2007 at 14:03:54 +0400, bash wrote: > > Im simplify environment: > > > > CREATE TABLE tbl( > > id integer NOT NULL PRIMARY KEY AUTOINCREMENT, > > n1 int, > > n2 int > > ); > > CREATE INDEX idx1 on tbl(n1); > > CREATE INDEX idx2 on tbl(n2); > > > > sqlite> select count(*) from tbl; > > 63026 > > > > 1 query: > > SELECT id, n1, n2 > > FROM tbl > > WHERE n1 = $I OR n2 = $I > > ORDER BY id DESC; > > > > 2 query: > > SELECT id, n1, n2 > > FROM tbl > > WHERE n1 = $I > > UNION > > SELECT id, n1, n2 > > FROM tbl > > WHERE n2 = $I > > ORDER BY id DESC; > > > > Timing: > > 1: 0.080 s. > > 2: 0.000 s. > > From http://www.sqlite.org/optoverview.html section 6.0: > > Each table in the FROM clause of a query can use at most one index... > > So the first query can't benefit from both idx1 and idx2. You may use > > EXPLAIN QUERY PLAN SELECT ... > > to see what indexes will be used. If i understand right from previous post by Peter there will be not used any indexes because of "OR". -- Biomechanical Artificial Sabotage Humanoid ----------------------------------------------------------------------------- To unsubscribe, send email to [EMAIL PROTECTED] -----------------------------------------------------------------------------
