Re: Re[2]: [HACKERS] using indexes

On Mon, 19 Oct 1998, Sferacarta Software wrote:

> Hi Tom,
>
>
> TGL> Jose' wrote:
> >>
> >> Hello all,
> >>
> >> I have a table SP with a primary key SNO,
> >> I'm trying if v6.4beta2 uses indexes
> >> but seems it uses indexes only with '=' operator:
>
> regression=>> explain select unique1 from onek where unique1 < 3;
> TGL> NOTICE: QUERY PLAN:
>
> TGL> Index Scan using onek_unique1 on onek (cost=28.67 size=334 width=4)
>
> >> prova=> explain select * from sp where sno = 'S1';
> >> NOTICE: QUERY PLAN:
> >> Index Scan using sp_pkey on sp (cost=0.00 size=0 width=28)
> >> EXPLAIN
>
> TGL> Looks like maybe you need to vacuum to get statistics for the optimizer?
>
> TGL> - Tom
>
>
> After vacuum the behavior is the same:
>
> prova=> create table onek(unique1 int4 primary key);
> NOTICE: CREATE TABLE/PRIMARY KEY will create implicit index onek_pkey
> for table onek
> CREATE
> prova=> insert into onek values (1);
> INSERT 152858 1
> prova=> insert into onek values (10);
> INSERT 152859 1
> prova=> explain select unique1 from onek where unique1 < 3;
> NOTICE: QUERY PLAN:
>
> Seq Scan on onek (cost=0.00 size=0 width=4)

The table has two records in it...why would it use an index?

Marc G. Fournier scrappy(at)hub(dot)org
Systems Administrator @ hub.org
scrappy(at){postgresql|isc}.org ICQ#7615664