dynamobi/dynamobi — Issue #569: [FRG-303] add values/empty reduction to default Farrago planner program
Author: dynamobi-build
Created: 2011-12-30 03:35:44+00:00
State: open
Labels: FRG, Optimization rules

[reporter="jvs", created="Wed, 2 Jan 2008 18:12:18 -0500 (GMT-05:00)"]
Julian introduced these in eigenchange 10365, with unit tests. FarragoReduceValuesRule and RemoveEmptyRule need to be added explicitly to the FarragoDefaultHeuristicPlanner program in order to take effect in SQL.

Seems like another useful rule would be FilterRel(AnyRel,false) => EmptyRel. This would allow a query like

select * from t where false

to come back immediately (always useful for getting the list of column names when you can't remember the metadata command).