org.eigenbase.rel
Class CollectRel

java.lang.Object
  org.eigenbase.rel.AbstractRelNode
      org.eigenbase.rel.SingleRel
          org.eigenbase.rel.CollectRel

All Implemented Interfaces:

Cloneable, RelNode

public final class CollectRel
extends SingleRel

A relational expression which collapses multiple rows into one.

Rules:

• FarragoMultisetSplitterRule creates a CollectRel from a call to SqlMultisetValueConstructor or to SqlMultisetQueryConstructor.

Since:

Dec 12, 2004

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rel/CollectRel.java#17 $

Author:

Wael Chatila

Field Summary

private String

fieldName

Fields inherited from class org.eigenbase.rel.AbstractRelNode

digest, id, nextId, rowType, traits

Fields inherited from interface org.eigenbase.rel.RelNode

emptyArray

Constructor Summary

CollectRel(RelOptCluster cluster, RelNode child, String fieldName)
Creates a CollectRel.

Method Summary

CollectRel	clone() Clones this RelNode.
static RelDataType	deriveCollectRowType(SingleRel rel, String fieldName) Derives the output type of a collect relational expression.
protected RelDataType	deriveRowType()
String	getFieldName() Returns the name of the sole output field.

Methods inherited from class org.eigenbase.rel.SingleRel

childrenAccept, explain, getChild, getInputs, getRows, replaceInput

Methods inherited from class org.eigenbase.rel.AbstractRelNode

cloneTraits, collectVariablesSet, collectVariablesUsed, computeDigest, computeSelfCost, getChildExps, getCluster, getCollationList, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getOrCreateCorrelVariable, getQuery, getRelTypeName, getRowType, getTable, getTraits, getVariablesStopped, inheritTraitsFrom, isAccessTo, isDistinct, isValid, onRegister, recomputeDigest, register, registerCorrelVariable, setCorrelVariable, toString

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

fieldName

private final String fieldName

Constructor Detail

CollectRel

public CollectRel(RelOptCluster cluster,
                  RelNode child,
                  String fieldName)

Creates a CollectRel.

Parameters:

cluster - Cluster

child - Child relational expression

fieldName - Name of the sole output field

Method Detail

clone

public CollectRel clone()

Description copied from interface: RelNode

Clones this RelNode.

Traits of the RelNode must be explicitly cloned, using AbstractRelNode.inheritTraitsFrom(AbstractRelNode), as the RelNode may have traits of which it has no knowledge. Example implementation:

     public MyRelNode clone()
     {
         MyRelNode clone = new MyRelNode(...);
         clone.inheritTraitsFrom(this);
         return clone;
     }
 

N.B.: This method must be overridden whenever an existing, concrete RelNode is extended. Otherwise, calling clone() will produce a differently typed RelNode, resulting in invalid or incorrect query plans.

Specified by:

clone in interface RelNode

Specified by:

clone in class AbstractRelNode

Returns:

a clone of this RelNode

getFieldName

public String getFieldName()

Returns the name of the sole output field.

Returns:

name of the sole output field

deriveRowType

protected RelDataType deriveRowType()

Overrides:

deriveRowType in class SingleRel

deriveCollectRowType

public static RelDataType deriveCollectRowType(SingleRel rel,
                                               String fieldName)

Derives the output type of a collect relational expression.

Parameters:

rel - relational expression

fieldName - name of sole output field

Returns:

output type of a collect relational expression