Class AbstractConverter.ExpandConversionRule

  extended by org.eigenbase.relopt.RelOptRule
      extended by org.eigenbase.relopt.volcano.AbstractConverter.ExpandConversionRule
Enclosing class:

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


public static final AbstractConverter.ExpandConversionRule instance
Constructor Detail


private AbstractConverter.ExpandConversionRule()
Creates an ExpandConversionRule.

Method Detail


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
call - Rule call
See Also: