Re: Why date index is not used

If you want to benefit from the usage of an index, the query has to
contain some WHERE conditions (on the indexed columns). This is a
'select all' query - there is no way to speed it up using index.

Tomas

> > Why Postgres 8.1 does not use makse_kuupaev_idx index in the
following query
> > ?
> >
> > How to speed this query up ?
> >
> > explain analyze select * from makse order by kuupaev desc, kellaaeg
desc
> > limit 100
> >
> > "Limit (cost=62907.94..62908.19 rows=100 width=876) (actual
> > time=33699.551..33701.001 rows=100 loops=1)"
> > " -> Sort (cost=62907.94..63040.49 rows=53022 width=876) (actual
> > time=33699.534..33700.129 rows=100 loops=1)"
> > " Sort Key: kuupaev, kellaaeg"
> > " -> Seq Scan on makse (cost=0.00..2717.22 rows=53022
width=876)
> > (actual time=0.020..308.502 rows=53028 loops=1)"
> > "Total runtime: 37857.177 ms"
> >
> >
> > CREATE TABLE makse(
> > kuupaev date,
> > kellaaeg char(6) NOT NULL DEFAULT ''::bpchar,
> > guid char(36) NOT NULL,
> > CONSTRAINT makse_pkey PRIMARY KEY (guid) )
> >
> >
> > CREATE INDEX makse_kuupaev_idx ON makse USING btree (kuupaev);