net.sf.saffron.rel.jdbc
Class AddFilterToQueryRule

java.lang.Object
  |
  +--net.sf.saffron.opt.VolcanoRule
        |
        +--net.sf.saffron.rel.jdbc.AddFilterToQueryRule

class AddFilterToQueryRule

extends VolcanoRule

AddFilterToQueryRule grafts a FilterRel onto a JdbcQuery.

This rule only works if the query's select clause is "*". If you start with a FilterRel on a ProjectRel on a JavaTableAccessRel, this will not be the case. You can fix it by pushing the filter through the project. (todo: Implement a rule to do this.)

Since:

Nov 26, 2003

Version:

$Id: $

Author:

jhyde

Field Summary

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

description, planner

Constructor Summary

(package private)

AddFilterToQueryRule()

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

AddFilterToQueryRule

AddFilterToQueryRule()

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