org.eigenbase.rel
Class UncollectRel

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

All Implemented Interfaces:

Cloneable, RelNode

public final class UncollectRel
extends SingleRel

A relational expression which unnests its input's sole column into a relation.

Like its inverse operation CollectRel, UncollectRel is generally invoked in a nested loop, driven by CorrelatorRel or similar.

Since:

Dec 12, 2004

Version:

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

Author:

Wael Chatila

Field Summary

Fields inherited from class org.eigenbase.rel.AbstractRelNode

digest, id, nextId, rowType, traits

Fields inherited from interface org.eigenbase.rel.RelNode

emptyArray

Constructor Summary

UncollectRel(RelOptCluster cluster, RelNode child)
Creates an UncollectRel.

Method Summary

UncollectRel	clone() Clones this RelNode.
protected RelDataType	deriveRowType()
static RelDataType	deriveUncollectRowType(RelNode rel) Returns the row type returned by applying the 'UNNEST' operation to a relational expression.

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

Constructor Detail

UncollectRel

public UncollectRel(RelOptCluster cluster,
                    RelNode child)

Creates an UncollectRel.

The row type of the child relational expression must contain precisely one column, that column must be a multiset of records.

Parameters:

cluster - Cluster the relational expression belongs to

child - Child relational expression

Method Detail

clone

public UncollectRel 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

deriveRowType

protected RelDataType deriveRowType()

Overrides:

deriveRowType in class SingleRel

deriveUncollectRowType

public static RelDataType deriveUncollectRowType(RelNode rel)

Returns the row type returned by applying the 'UNNEST' operation to a relational expression. The relational expression must have precisely one column, whose type must be a multiset of structs. The return type is the type of that column.