Class RemoveTrivialProjectRule

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

public class RemoveTrivialProjectRule
extends RelOptRule

Rule which, given a ProjectRel node which merely returns its input, converts the node into its child.

For example, ProjectRel(ArrayReader(a), {$input0}) becomes ArrayReader(a).

See Also:

Field Summary
static RemoveTrivialProjectRule instance
Fields inherited from class org.eigenbase.relopt.RelOptRule
ANY, description, operands
Constructor Summary
private RemoveTrivialProjectRule()
Method Summary
static boolean isIdentity(RexNode[] exps, RelDataType rowType, RelDataType childRowType)
 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 RemoveTrivialProjectRule instance
Constructor Detail


private RemoveTrivialProjectRule()
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:


public static boolean isIdentity(RexNode[] exps,
                                 RelDataType rowType,
                                 RelDataType childRowType)