Type casting

Hi!

 I've got following structure:
CREATE TABLE test ( field1 int8 );

CREATE INDEX test_ndx ON test USING btree (field1);

 But when I execute following Java code:

  PreparedStatement pstmt = con.prepareStatement("SELECT field1 FROM
test WHERE field1=?;");
  pstmt.setLong(1, 1);
  pstmt.executeQuery();

 it doesn't use created index.
When I change my code:

  PreparedStatement pstmt = con.prepareStatement("SELECT field1 FROM
test WHERE field1=int8(?);");
  pstmt.setLong(1, 1);
  pstmt.executeQuery();

then it uses index.
My question is: Shouldn't JDBC Driver automatically cast type basing on
methods setLong, setInt etc. ? You can say: "Change your code, what's
your problem?". But I don't know which database I will use and not all
databases has int8() functions (I think so.). If you know what i mean.
Can you help me ?

P.S. I'm using PostgreSQL 7.3 with last PgSQL JDBC3 Driver.
"PostgreSQL Native Driver (ver.:PostgreSQL 7.3 JDBC3 jdbc driver build
106)"

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Best regards,
 Marek Kaluzny