SemiJoinRemoveRule (Apache Calcite API)

java.lang.Object
- org.apache.calcite.plan.RelOptRule
- - org.apache.calcite.rel.rules.SemiJoinRemoveRule

```
public class SemiJoinRemoveRule
extends RelOptRule
```
Planner rule that removes a SemiJoins from a join tree.
It is invoked after attempts have been made to convert a SemiJoin to an indexed scan on a join factor have failed. Namely, if the join factor does not reduce to a single table that can be scanned using an index.
It should only be enabled if all SemiJoins in the plan are advisory; that is, they can be safely dropped without affecting the semantics of the query.

- Field Summary
  
  Fields
  Modifier and Type Field Description
  
  static SemiJoinRemoveRule INSTANCE
  - Fields inherited from class org.apache.calcite.plan.RelOptRule
    description, operands, relBuilderFactory
- Constructor Summary
  
  Constructors
  Constructor Description
  
  SemiJoinRemoveRule(RelBuilderFactory relBuilderFactory)
  Creates a SemiJoinRemoveRule.
- Method Summary
  
  All Methods Instance Methods Concrete Methods
  Modifier and Type Method Description
  
  void onMatch(RelOptRuleCall call)
  Receives notification about a rule match.
  - Methods inherited from class org.apache.calcite.plan.RelOptRule
    any, convert, convert, convertList, convertOperand, convertOperand, equals, equals, getOperand, getOperands, getOutConvention, getOutTrait, hashCode, matches, none, operand, operand, operand, operand, operand, operandJ, operandJ, some, toString, unordered
  - Methods inherited from class java.lang.Object
    clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - INSTANCE
```
public static final SemiJoinRemoveRule INSTANCE
```
- Constructor Detail
  - SemiJoinRemoveRule
```
public SemiJoinRemoveRule(RelBuilderFactory relBuilderFactory)
```
    Creates a SemiJoinRemoveRule.
- 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.apache.calcite.rel.RelNode, java.util.Map<org.apache.calcite.rel.RelNode, org.apache.calcite.rel.RelNode>) to register the expression.
    
    Specified by:
    
    onMatch in class RelOptRule
    
    Parameters:
    
    call - Rule call
    
    See Also:
    
    RelOptRule.matches(RelOptRuleCall)