Package org.apache.calcite.rel.core

Class RepeatUnion

java.lang.Object

org.apache.calcite.rel.AbstractRelNode

org.apache.calcite.rel.BiRel

org.apache.calcite.rel.core.RepeatUnion

All Implemented Interfaces:

Cloneable, RelOptNode, RelNode

Direct Known Subclasses:

EnumerableRepeatUnion, LogicalRepeatUnion

public abstract class RepeatUnion
extends BiRel

Relational expression that computes a repeat union (recursive union in SQL terminology).

This operation is executed as follows:

• Evaluate the left input (i.e., seed relational expression) once. For UNION (but not UNION ALL), discard duplicated rows.
• Evaluate the right input (i.e., iterative relational expression) over and over until it produces no more results (or until an optional maximum number of iterations is reached). For UNION (but not UNION ALL), discard duplicated results.

NOTE: The current API is experimental and subject to change without notice.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.calcite.rel.RelNode

RelNode.Context

Field Summary

Fields

Modifier and Type	Field	Description
boolean	all	Whether duplicates are considered.
int	iterationLimit	Maximum number of times to repeat the iterative relational expression; negative value means no limit, 0 means only seed will be evaluated.

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

left, right

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

digest, id, rowType, traitSet

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	RepeatUnion(RelOptCluster cluster, RelTraitSet traitSet, RelNode seed, RelNode iterative, boolean all, int iterationLimit)

Method Summary

Modifier and Type	Method	Description
protected RelDataType	deriveRowType()
double	estimateRowCount(RelMetadataQuery mq)	Returns an estimate of the number of rows this relational expression will return.
RelWriter	explainTerms(RelWriter pw)	Describes the inputs and attributes of this relational expression.
RelNode	getIterativeRel()
RelNode	getSeedRel()

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

childrenAccept, getInputs, getLeft, getRight, replaceInput

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

accept, accept, collectVariablesSet, collectVariablesUsed, computeSelfCost, copy, deepEquals, deepHashCode, equals, explain, getCluster, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getRelDigest, getRelTypeName, getRowType, getTable, getTraitSet, getVariablesSet, hashCode, isEnforcer, isValid, metadata, onRegister, recomputeDigest, register, sole, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.calcite.rel.RelNode

explain

Field Details

all

public final boolean all

Whether duplicates are considered.

iterationLimit

public final int iterationLimit

Maximum number of times to repeat the iterative relational expression; negative value means no limit, 0 means only seed will be evaluated.

Constructor Details

RepeatUnion

protected RepeatUnion(RelOptCluster cluster, RelTraitSet traitSet, RelNode seed, RelNode iterative, boolean all, int iterationLimit)

Method Details

estimateRowCount

public double estimateRowCount(RelMetadataQuery mq)

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:

estimateRowCount in interface RelNode

Overrides:

estimateRowCount in class AbstractRelNode

Parameters:

mq - Metadata query

Returns:

Estimate of the number of rows this relational expression will return

explainTerms

public RelWriter explainTerms(RelWriter pw)

Description copied from class: AbstractRelNode

Describes the inputs and attributes of this relational expression. Each node should call super.explainTerms, then call the RelWriter.input(String, RelNode) and RelWriterImpl.item(String, Object) methods for each input and attribute.

Overrides:

explainTerms in class BiRel

Parameters:

pw - Plan writer

Returns:

Plan writer for fluent-explain pattern

getSeedRel

public RelNode getSeedRel()

getIterativeRel

public RelNode getIterativeRel()

deriveRowType

protected RelDataType deriveRowType()

Overrides:

deriveRowType in class AbstractRelNode