1. Can anyone pls explain what the impact of not specifiying Targets in Business Rules - Workbench would be? In the Preview Reference Application, I see that all records are returned for those rules. Does this mean that when these rules are firing on the website, they are actually making internal calls to the MDEX for all records?
2. If the response to #1 is yes, then if we have 3 such rules trigger promotions on our Homepage, and they are not clicked on by users, then will the mere presence of them on the page still trigger the call to the mdex?
If you don't specify a Target in the business rules, then Endeca will effectively execute an N=0 and return the records as specified in the accompanying Style (i.e. if Maximum Records is set to 10, it will return the first 10 records in the index). I'm not sure on what your use case is though - the only time I've ever set up a rule with an empty target is to use the "Augment Navigation State" (can't remember what the term is in Workbench, something like "apply to current navigation" I think) and use a different sort order to create a dynamic subset of the current results (to show, for example, the "most recent" results by sorting the relevance-ordered results by publication date).
If you have rules that you want to avoid firing in certain occasions, a handy feature is the "merchandising rule filter". Have a look in the documentation - it gives you the option to specify a statement that can be used to include/exclude business rules (e.g. if the rules had a custom property of "Include_In_Global_Search" added to them, you could use a rule filter of &Nmrf=NOT(Include_In_Global_Search:Y) to ensure those rules got excluded in certain occasions.
Generally used to create deafult business rule which can be applied, if none of them rule fire.
In your case, rule get fired which is very much same as none fired and even default cannot be applied in this case.
I am not sure if there is a way to make such rule invalid which might help.
Michael point is correct but if rules are uploaded in bulk very difficult to find out which has target and which donot. It might also be a miss to specify target.
By making invalid in xml rule can trigger atleast default rule.