net.sf.saffron.oj
Class OJPlannerFactory.DistinctToExistsRule

java.lang.Object
  |
  +--net.sf.saffron.opt.VolcanoRule
        |
        +--net.sf.saffron.oj.OJPlannerFactory.DistinctToExistsRule

Enclosing class:

OJPlannerFactory

public static class OJPlannerFactory.DistinctToExistsRule

extends VolcanoRule

Rule to translate a JavaDistinctRel into a JavaExistsRel, provided that the select list contains zero columns.

Field Summary

Fields inherited from class net.sf.saffron.opt.VolcanoRule

description, planner

Constructor Summary

OJPlannerFactory.DistinctToExistsRule()

Method Summary

void	onMatch(VolcanoRuleCall call) This method is called every time the rule matches.

Methods inherited from class net.sf.saffron.opt.VolcanoRule

convert, getOutConvention, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

OJPlannerFactory.DistinctToExistsRule

public OJPlannerFactory.DistinctToExistsRule()

Method Detail

onMatch

public void onMatch(VolcanoRuleCall call)

Description copied from class: VolcanoRule

This method is called every time the rule matches. At the time that this method is called, call.rels holds the set of relational expressions which match the operands to the rule; call.rels[0] is the root expression.

Typically a rule would check that the nodes are valid matches, creates a new expression, then calls back VolcanoRuleCall.transformTo(net.sf.saffron.rel.SaffronRel) to register the expression.

Specified by:

onMatch in class VolcanoRule