For broadcast hint, we accept "BROADCAST", "BROADCASTJOIN", and "MAPJOIN", and a sequence of relation aliases can be specified in the hint.
For broadcast hint, we accept "BROADCAST", "BROADCASTJOIN", and "MAPJOIN", and a sequence of relation aliases can be specified in the hint. A broadcast hint plan node will be inserted on top of any relation (that is not aliased differently), subquery, or common table expression that match the specified name.
The hint resolution works by recursively traversing down the query plan to find a relation or subquery that matches one of the specified broadcast aliases. The traversal does not go past beyond any existing broadcast hints, subquery aliases.
This rule must happen before common table expressions.
Removes all the hints, used to remove invalid hints provided by the user.
Removes all the hints, used to remove invalid hints provided by the user. This must be executed after all the other hint rules are executed.
Collection of rules related to hints. The only hint currently available is broadcast join hint.
Note that this is separately into two rules because in the future we might introduce new hint rules that have different ordering requirements from broadcast.