:c
In a directed query, marks a query constant that must be included in an input query; otherwise, that input query is disqualified from using the directed query.
In a directed query, marks a query constant that must be included in an input query; otherwise, that input query is disqualified from using the directed query.
Syntax
/*+:c*/
Usage
By default, optimizer-generated directed queries set ignore constant (:v) hints on predicate constants. You can override this behavior by setting the :c hint on input query constants that must not be ignored. For example, the following statement creates a directed query that can be used only for input queries where the join predicate constant is the same as in the original input query—8:
=> CREATE DIRECTED QUERY OPTIMIZER simpleJoin_KeepPredicateConstant SELECT * FROM S JOIN T ON S.a = T.b WHERE S.a = 8 /*+:c*/;
CREATE DIRECTED QUERY
=> ACTIVATE DIRECTED QUERY simpleJoin_KeepPredicateConstant;