org.eigenbase.relopt.volcano
Class AbstractConverter.ExpandConversionRule

java.lang.Object
  org.eigenbase.relopt.RelOptRule
      org.eigenbase.relopt.volcano.AbstractConverter.ExpandConversionRule

Enclosing class:

AbstractConverter

public static class AbstractConverter.ExpandConversionRule
extends RelOptRule

Rule which converts an AbstractConverter into a chain of converters from the source relation to the target traits.

The chain produced is mimimal: we have previously built the transitive closure of the graph of conversions, so we choose the shortest chain.

Unlike the AbstractConverter they are replacing, these converters are guaranteed to be able to convert any relation of their calling convention. Furthermore, because they introduce subsets of other calling conventions along the way, these subsets may spawn more efficient conversions which are not generally applicable.

AbstractConverters can be messy, so they restrain themselves: they don't fire if the target subset already has an implementation (with less than infinite cost).

Field Summary

static AbstractConverter.ExpandConversionRule

instance

Fields inherited from class org.eigenbase.relopt.RelOptRule

ANY, description, operands

Constructor Summary

private

AbstractConverter.ExpandConversionRule() Creates an ExpandConversionRule.

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

Field Detail

instance

public static final AbstractConverter.ExpandConversionRule instance

Constructor Detail

AbstractConverter.ExpandConversionRule

private AbstractConverter.ExpandConversionRule()

Creates an ExpandConversionRule.

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)