Bug #474: Index using problem

JoE Olcsak (joe78(at)freemail(dot)hu) reports a bug with a severity of 4
The lower the number the more severe it is.

Short Description
Index using problem

Long Description
I have a problem when using indexes under PostgreSQL 7.1.1 ...

The problem is :

I have a field of table ... This is an INT4 type field ... and I
created an index for this field like :
create index idx_of_field on cim(utod_cim_id);
... and I executed a simple query ...

explain select * from cim where utod_cim_id=0;

NOTICE: QUERY PLAN:

Seq Scan on cim (cost=0.00..6555.41 rows=253633 width=118)

EXPLAIN

The query optimizer does not use my index..

I'm executed vacuum analyze command for this table but this not helps me ...

Then I created another index for this field:

create index idx_of_field2 on cim(int4(utod_cim_id));

... and I executed another simple query :

explain select * from cim where int4(utod_cim_id)=0;
NOTICE: QUERY PLAN:

Index Scan using idx_of_field2 on cim (cost=0.00..6499.70 rows=2536 width=118)

EXPLAIN

What is wrong in the first case ?

Sample Code

No file was uploaded with this report