UnionMergeRule (Apache Calcite API)

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

```
public class UnionMergeRule
extends RelOptRule
```
UnionMergeRule implements the rule for combining two non-distinct SetOps into a single SetOp.
Originally written for Union (hence the name), but now also applies to Intersect.

Field Summary

Fields
Modifier and Type Field Description

static UnionMergeRule INSTANCE

static UnionMergeRule INTERSECT_INSTANCE

static UnionMergeRule MINUS_INSTANCE
- Fields inherited from class org.apache.calcite.plan.RelOptRule
  description, operands, relBuilderFactory

Constructor Summary

Constructors
Constructor	Description
`UnionMergeRule(java.lang.Class<? extends SetOp> unionClazz, java.lang.String description, RelBuilderFactory relBuilderFactory)`	Creates a UnionMergeRule.
`UnionMergeRule(java.lang.Class<? extends Union> unionClazz, RelFactories.SetOpFactory setOpFactory)`	Deprecated.

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 UnionMergeRule INSTANCE
```
  - INTERSECT_INSTANCE
```
public static final UnionMergeRule INTERSECT_INSTANCE
```
  - MINUS_INSTANCE
```
public static final UnionMergeRule MINUS_INSTANCE
```
- Constructor Detail
  - UnionMergeRule
```
public UnionMergeRule(java.lang.Class<? extends SetOp> unionClazz,
                      java.lang.String description,
                      RelBuilderFactory relBuilderFactory)
```
    Creates a UnionMergeRule.
  - UnionMergeRule
```
@Deprecated
public UnionMergeRule(java.lang.Class<? extends Union> unionClazz,
                      RelFactories.SetOpFactory setOpFactory)
```
    Deprecated.
- 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)