Restrictions on External Tables in Joins and Subqueries

In Extended Parallel Server, when you use external tables in joins or subqueries, the following restrictions apply:

• No more than one external table is valid in a query.
• The external table cannot be the outer table in an outer join.
• For subqueries that cannot be converted to joins, you can use an external table in the main query, but not the subquery.
• You cannot do a self-join on an external table.

For more information on subqueries, see your IBM Informix Performance Guide.