org.apache.calcite.rel.core

Class Union

java.lang.Object

org.apache.calcite.rel.AbstractRelNode

org.apache.calcite.rel.core.SetOp

org.apache.calcite.rel.core.Union

All Implemented Interfaces:

Cloneable, RelOptNode, RelNode

Direct Known Subclasses:

Bindables.BindableUnion, EnumerableUnion, JdbcRules.JdbcUnion, LogicalUnion

public abstract class Union
extends SetOp

Relational expression that returns the union of the rows of its inputs, optionally eliminating duplicates.

Corresponds to SQL UNION and UNION ALL.

Field Summary

Fields inherited from class org.apache.calcite.rel.core.SetOp

all, inputs, kind

Fields inherited from class org.apache.calcite.rel.AbstractRelNode

digest, id, rowType, traitSet

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Union(RelInput input) Creates a Union by parsing serialized output.
protected	Union(RelOptCluster cluster, RelTraitSet traits, List<RelNode> inputs, boolean all)

Method Summary

Methods

Modifier and Type	Method and Description
static double	estimateRowCount(RelNode rel) Helper method for computing row count for UNION ALL.
double	getRows() Returns an estimate of the number of rows this relational expression will return.

Methods inherited from class org.apache.calcite.rel.core.SetOp

copy, copy, deriveRowType, explainTerms, getInputs, isHomogeneous, isKey, replaceInput

Methods inherited from class org.apache.calcite.rel.AbstractRelNode

accept, accept, childrenAccept, collectVariablesSet, collectVariablesUsed, computeDigest, computeSelfCost, explain, getChildExps, getCluster, getCollationList, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getQuery, getRelTypeName, getRowType, getTable, getTraitSet, getVariablesStopped, isDistinct, isValid, metadata, onRegister, recomputeDigest, register, sole, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

Union

protected Union(RelOptCluster cluster,
     RelTraitSet traits,
     List<RelNode> inputs,
     boolean all)

Union

protected Union(RelInput input)

Creates a Union by parsing serialized output.

Method Detail

getRows

public double getRows()

Description copied from interface: RelNode

Returns an estimate of the number of rows this relational expression will return.

NOTE jvs 29-Mar-2006: Don't call this method directly. Instead, use RelMetadataQuery.getRowCount(org.apache.calcite.rel.RelNode), which gives plugins a chance to override the rel's default ideas about row count.

Specified by:

getRows in interface RelNode

Overrides:

getRows in class AbstractRelNode

Returns:

Estimate of the number of rows this relational expression will return

estimateRowCount

public static double estimateRowCount(RelNode rel)

Helper method for computing row count for UNION ALL.

Parameters:

rel - node representing UNION ALL

Returns:

estimated row count for rel