At this time, an attribute set associated with an expression column cannot be edited (adding new attributes or deleting some attributes). The index and the trigger created to maintain the expression column are closely tied with the attribute set. So, you will have to drop the Expression Filter index and unassign the attribute set in order to recreate the attributes.- Can I add or delete and attribute to an existing attribute set?. The idea would be to provide users with the ability to add or delete attributes of interest through the use of some metadata. If not, what would be the implications of recreating the attributes, since there are several objects related to an attribute set(types, triggers, etc.).
Yes, this can be done by specifying additional predicates in the query with EVALUATE operator. For example, the following query only evaluates the expression associated with a specific customer.- Can i evaluate expressions on a one by one basis?. The example showed always evaluate all expressions at the same time. My idea here, would be give the users the possibility of specifying the frequency of evaluating a particular expression, since all might not be equally important.
Yes, you can use user-defined functions in the stored expressions. See Example 10.3 in the Application Developer's Guide - Rules Manager and Expression Filter (10g Release 2) for a sample.- Can i use the result of a pl/sql function and use it in an expression set. Again, sometimes things might be more complicated than evaluating columns of a table on a expression.