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

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University of Illinois

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