net.sf.farrago.query
Class FarragoReduceValuesRule

java.lang.Object
  org.eigenbase.relopt.RelOptRule
      net.sf.farrago.query.FarragoReduceValuesRule

public abstract class FarragoReduceValuesRule
extends RelOptRule

Planner rule which folds projections and filters into an underlying ValuesRel. Returns an EmptyRel if all rows are filtered away.

For example,

select a - b from (values (1, 2), (3, 5), (7, 11)) as t (a, b) where a + b > 4

becomes

select x from (values (-2), (-4))

Version:

$Id: //open/dev/farrago/src/net/sf/farrago/query/FarragoReduceValuesRule.java#7 $

Author:

jhyde

Nested Class Summary

private static class

FarragoReduceValuesRule.MyRexShuttle

Field Summary

static FarragoReduceValuesRule	filterInstance Singleton instance of this rule which applies to the pattern Filter(Values).
static FarragoReduceValuesRule	projectFilterInstance Singleton instance of this rule which applies to the pattern Project(Filter(Values)).
static FarragoReduceValuesRule	projectInstance Singleton instance of this rule which applies to the pattern Project(Values).
private static Logger	tracer

Fields inherited from class org.eigenbase.relopt.RelOptRule

ANY, description, operands

Constructor Summary

private

FarragoReduceValuesRule(RelOptRuleOperand operand, String desc) Creates a new FarragoReduceExpressionsRule object.

Method Summary

protected void

apply(RelOptRuleCall call, ProjectRel project, FilterRel filter, ValuesRel values) Does the work.

Methods inherited from class org.eigenbase.relopt.RelOptRule

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

Methods inherited from class java.lang.Object

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

Field Detail

tracer

private static final Logger tracer

filterInstance

public static final FarragoReduceValuesRule filterInstance

Singleton instance of this rule which applies to the pattern Filter(Values).

projectInstance

public static final FarragoReduceValuesRule projectInstance

Singleton instance of this rule which applies to the pattern Project(Values).

projectFilterInstance

public static final FarragoReduceValuesRule projectFilterInstance

Singleton instance of this rule which applies to the pattern Project(Filter(Values)).

Constructor Detail

FarragoReduceValuesRule

private FarragoReduceValuesRule(RelOptRuleOperand operand,
                                String desc)

Creates a new FarragoReduceExpressionsRule object.

Parameters:

operand - class of rels to which this rule should apply

Method Detail

apply

protected void apply(RelOptRuleCall call,
                     ProjectRel project,
                     FilterRel filter,
                     ValuesRel values)

Does the work.

Parameters:

call - Rule call

project - Project, may be null

filter - Filter, may be null

values - Values rel to be reduced