Creating a foreign key

PostgreSQL: 8.2

When you create a foreign key to a table is there an index that is
created on the foreign key automatically?

Example:

Table A has a field called ID.

Table B has a field called fk_a_id which has a constraint of being a
foreign key to table A to field ID.

Is there an index automatically created on field fk_a_id in table B when
I create a foreign key constraint?

I assume yes. But I wanted to check. I did not see it specifically
mentioned in the documentation.

I also see "CREATE TABLE / PRIMARY KEY will create implicit index" when
creating a primary key but I don't see any similar statement when
creating a foreign key.

Thanks,

Lance Campbell

Project Manager/Software Architect

Web Services at Public Affairs

University of Illinois

217.333.0382

http://webservices.uiuc.edu