Class RemoveSemiJoinRule

  extended by org.eigenbase.relopt.RelOptRule
      extended by org.eigenbase.rel.rules.RemoveSemiJoinRule

public class RemoveSemiJoinRule
extends RelOptRule

RemoveSemiJoinRule implements the rule that removes semijoins from a join tree if it turns out it's not possible to convert a SemiJoinRel to an indexed scan on a join factor. Namely, if the join factor does not reduce to a single table that can be scanned using an index. This rule should only be applied after attempts have been made to convert SemiJoinRels.

$Id: //open/dev/farrago/src/org/eigenbase/rel/rules/ $
Zelaine Fong

Field Summary
static RemoveSemiJoinRule instance
Fields inherited from class org.eigenbase.relopt.RelOptRule
ANY, description, operands
Constructor Summary
private RemoveSemiJoinRule()
          Creates a RemoveSemiJoinRule.
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 RemoveSemiJoinRule instance
Constructor Detail


private RemoveSemiJoinRule()
Creates a RemoveSemiJoinRule.

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: