org.eigenbase.rel.jdbc
Class AddProjectToQueryRule

java.lang.Object
  org.eigenbase.relopt.RelOptRule
      org.eigenbase.rel.jdbc.AddProjectToQueryRule

 class AddProjectToQueryRule
extends RelOptRule

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/dev/farrago/src/org/eigenbase/rel/jdbc/AddProjectToQueryRule.java#15 $

Author:

jhyde

Field Summary

Fields inherited from class org.eigenbase.relopt.RelOptRule

ANY, description, operands

Constructor Summary

AddProjectToQueryRule()

Method Summary

void	onMatch(RelOptRuleCall call) Receives notification about a rule match.

Methods inherited from class org.eigenbase.relopt.RelOptRule

convert, equals, equals, getOperand, getOperands, getOutConvention, getOutTrait, hashCode, matches, mergeTraitsAndConvert, mergeTraitsAndConvert, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

AddProjectToQueryRule

AddProjectToQueryRule()

Method Detail

onMatch

public void onMatch(RelOptRuleCall call)

Description copied from class: RelOptRule

Receives notification about a rule match. 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 RelOptRuleCall.transformTo(org.eigenbase.rel.RelNode) to register the expression.

Specified by:

onMatch in class RelOptRule

Parameters:

call - Rule call

See Also:

RelOptRule.matches(RelOptRuleCall)