BIGINT datatype and Indexes Failure

Hi to all!
    Is it possible to define indexes on a column with BIGINT datatype? See
this example:

testdb=# create table a (col1 integer not null primary key);
NOTICE:  CREATE TABLE/PRIMARY KEY will create implicit index 'a_pkey' for
table 'a'
CREATE
testdb=# create table b (col1 bigint not null primary key);
NOTICE:  CREATE TABLE/PRIMARY KEY will create implicit index 'b_pkey' for
table 'b'
CREATE
testdb=# explain select * from a where col1=123;
NOTICE:  QUERY PLAN:

Index Scan using a_pkey on a  (cost=0.00..8.14 rows=10 width=4)

EXPLAIN
testdb=# explain select * from b where col1=123;
NOTICE:  QUERY PLAN:

Seq Scan on b  (cost=0.00..22.50 rows=10 width=8)

On table a (INTEGER datatype) the search is done using the index.
Instead on table b (BIGINT datatype) the search is always done using the
seq scan.

Is it a bug?

I use Postgresql 7.1.2 on RedHat 7.1. All the regress tests has been
completed correctely during installation.

Please, let me know as soon as possible...

Regards,

Eng. Denis Gasparin: denis@edistar.com
---------------------------
Programmer & System Administrator - Edistar srl