[johnsg6977]

Hi,
Probably a silly question. When I create a foreign key on a table, I note an index is created on the foreign key column.

If I use that same column for other querying/searches, is it necessary to create a seperate index on that same column, or is the foreign key index already serving the purpose?

Thanks,
John.

[zxq9]

The created index will be used.

[Jacques1]

Hi,

Originally Posted by johnsg6977

When I create a foreign key on a table, I note an index is created on the foreign key column.

No, it's not:

Originally Posted by http://www.postgresql.org/docs/9.3/static/ddl-constraints.html#DDL-CONSTRAINTS-FK

[...] declaration of a foreign key constraint does not automatically create an index on the referencing columns.

Originally Posted by johnsg6977

If I use that same column for other querying/searches, is it necessary to create a seperate index on that same column, or is the foreign key index already serving the purpose?

Apart from the fact that PostgreSQL does not automatically create that index: It depends on the concrete query. There are many different types of indexes for different purposes. You may be able to use the same index for a foreign key constraint as well as a particular query. But there's no guarantee for it, and it may not be optimal.