Enable view folding to improve query performance

You can significantly improve the performance of a query that involves a view by enabling view folding.

You do this by setting the IFX_FOLDVIEW configuration parameter to 1.

When view folding is enabled, views are folded into a parent query. Because the views are folded into the parent query, the query results are not placed in a temporary table.

You can use view folding in the following types of queries:
  • Views that contain a UNION ALL clause and the parent query incldues a regular join, Informix® join, ANSI join, or an ORDER BY clause

View folding does not occur for the following types of queries that perform a UNION ALL operation involving a view:

  • The view has one of the following clauses: AGGREGATE, GROUP BY, ORDER BY, UNION, DISTINCT, or OUTER JOIN (either Informix® or ANSI type).
  • The parent query has a UNION or UNION ALL clause.
In these situations, a temporary table is created to hold query results.