net.sf.saffron.rel.jdbc
Class AddProjectToQueryRule

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

class AddProjectToQueryRule
extends VolcanoRule

A AddProjectToQueryRule grafts a ProjectRel onto a JdbcQuery. This rule does not apply if the query already has a select list (other than the default, null, which means '*'). todo: Write a rule to fuse two ProjectRels together.

Since:
Aug 7, 2002
Version:
$Id: //open/saffron/src/net/sf/saffron/rel/jdbc/AddProjectToQueryRule.java#3 $
Author:
jhyde

Field Summary
 
Fields inherited from class net.sf.saffron.opt.VolcanoRule
description, planner
 
Constructor Summary
(package private) AddProjectToQueryRule()
           
 
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

AddProjectToQueryRule

AddProjectToQueryRule()
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

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