org.apache.calcite.plan.volcano

Class RelSubset

java.lang.Object

org.apache.calcite.rel.AbstractRelNode

org.apache.calcite.plan.volcano.RelSubset

All Implemented Interfaces:

Cloneable, RelOptNode, RelNode

public class RelSubset
extends AbstractRelNode

Subset of an equivalence class where all relational expressions have the same physical properties.

Physical properties are instances of the RelTraitSet, and consist of traits such as calling convention and collation (sort-order).

For some traits, a relational expression can have more than one instance. For example, R can be sorted on both [X] and [Y, Z]. In which case, R would belong to the sub-sets for [X] and [Y, Z]; and also the leading edges [Y] and [].

See Also:

RelNode, RelSet, RelTrait

Nested Class Summary

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

RelNode.Context

Field Summary

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

digest, id, rowType, traitSet

Method Summary

Modifier and Type	Method and Description
void	collectVariablesSet(Set<CorrelationId> variableSet) Collects variables set by this expression.
void	collectVariablesUsed(Set<CorrelationId> variableSet) Collects variables known to be used by this expression or its descendants.
RelOptCost	computeSelfCost(RelOptPlanner planner, RelMetadataQuery mq) Returns the cost of this plan (not including children).
RelNode	copy(RelTraitSet traitSet, List<RelNode> inputs) Creates a copy of this relational expression, perhaps changing traits and inputs.
boolean	deepEquals(Object obj) Equality check for RelNode digest.
int	deepHashCode() Compute hash code for RelNode digest.
protected RelDataType	deriveRowType()
double	estimateRowCount(RelMetadataQuery mq) Returns an estimate of the number of rows this relational expression will return.
void	explain(RelWriter pw) Describes the inputs and attributes of this relational expression.
RelNode	getBest()
String	getDigest() Returns a digest string of this RelNode.
RelNode	getOriginal()
Collection<RelNode>	getParentRels() Returns a list of relational expressions one of whose children is this subset.
List<RelNode>	getRelList() As getRels() but returns a list.
Iterable<RelNode>	getRels() Returns the rel nodes in this rel subset.
Stream<RelSubset>	getSatisfyingSubsets() Returns stream of subsets whose traitset is satisfied by current subset's traitset.
Stream<RelSubset>	getSubsetsSatisfyingThis() Returns stream of subsets whose traitset satisfies current subset's traitset.
RelOptCost	getWinnerCost() Returns the best cost if this subset is fully optimized or null if the subset is not fully optimized.
boolean	isDelivered()
boolean	isRequired()

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

accept, accept, childrenAccept, equals, explainTerms, getCluster, getConvention, getCorrelVariable, getDescription, getExpectedInputRowType, getId, getInput, getInputs, getRelDigest, getRelTypeName, getRowType, getTable, getTraitSet, getVariablesSet, hashCode, isEnforcer, isValid, metadata, onRegister, recomputeDigest, register, replaceInput, 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

Method Detail

isDelivered

@API(since="1.23",
     status=EXPERIMENTAL)
public boolean isDelivered()

isRequired

@API(since="1.23",
     status=EXPERIMENTAL)
public boolean isRequired()

getBest

public RelNode getBest()

getOriginal

public RelNode getOriginal()

copy

public RelNode copy(RelTraitSet traitSet,
                    List<RelNode> inputs)

Description copied from interface: RelNode

Creates a copy of this relational expression, perhaps changing traits and inputs.

Sub-classes with other important attributes are encouraged to create variants of this method with more parameters.

Specified by:

copy in interface RelNode

Overrides:

copy in class AbstractRelNode

Parameters:

traitSet - Trait set

inputs - Inputs

Returns:

Copy of this relational expression, substituting traits and inputs

computeSelfCost

public RelOptCost computeSelfCost(RelOptPlanner planner,
                                  RelMetadataQuery mq)

Description copied from interface: RelNode

Returns the cost of this plan (not including children). The base implementation throws an error; derived classes should override.

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

Specified by:

computeSelfCost in interface RelNode

Overrides:

computeSelfCost in class AbstractRelNode

Parameters:

planner - Planner for cost calculation

mq - Metadata query

Returns:

Cost of this plan (not including children)

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

explain

public void explain(RelWriter pw)

Description copied from interface: RelNode

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

Specified by:

explain in interface RelNode

Overrides:

explain in class AbstractRelNode

Parameters:

pw - Plan writer

deepEquals

public boolean deepEquals(Object obj)

Description copied from class: AbstractRelNode

Equality check for RelNode digest.

By default this method collects digest attributes from AbstractRelNode.explainTerms(RelWriter), then compares each attribute pair. This should work well for most cases. If this method is a performance bottleneck for your project, or the default behavior can't handle your scenario properly, you can choose to override this method and AbstractRelNode.deepHashCode(). See LogicalJoin as an example.

Specified by:

deepEquals in interface RelNode

Overrides:

deepEquals in class AbstractRelNode

Returns:

Whether the 2 RelNodes are equivalent or have the same digest.

See Also:

AbstractRelNode.deepHashCode()

deepHashCode

public int deepHashCode()

Description copied from class: AbstractRelNode

Compute hash code for RelNode digest.

Specified by:

deepHashCode in interface RelNode

Overrides:

deepHashCode in class AbstractRelNode

See Also:

AbstractRelNode.deepEquals(Object)

deriveRowType

protected RelDataType deriveRowType()

Overrides:

deriveRowType in class AbstractRelNode

getParentRels

public Collection<RelNode> getParentRels()

Returns a list of relational expressions one of whose children is this subset. The elements of the list are distinct.

collectVariablesUsed

public void collectVariablesUsed(Set<CorrelationId> variableSet)

Description copied from interface: RelNode

Collects variables known to be used by this expression or its descendants. By default, no such information is available and must be derived by analyzing sub-expressions, but some optimizer implementations may insert special expressions which remember such information.

Specified by:

collectVariablesUsed in interface RelNode

Overrides:

collectVariablesUsed in class AbstractRelNode

Parameters:

variableSet - receives variables used

collectVariablesSet

public void collectVariablesSet(Set<CorrelationId> variableSet)

Description copied from interface: RelNode

Collects variables set by this expression. TODO: is this required?

Specified by:

collectVariablesSet in interface RelNode

Overrides:

collectVariablesSet in class AbstractRelNode

Parameters:

variableSet - receives variables known to be set by

getRels

public Iterable<RelNode> getRels()

Returns the rel nodes in this rel subset. All rels must have the same traits and are logically equivalent.

Returns:

all the rels in the subset

getRelList

public List<RelNode> getRelList()

As getRels() but returns a list.

getSubsetsSatisfyingThis

@API(since="1.23",
     status=EXPERIMENTAL)
public Stream<RelSubset> getSubsetsSatisfyingThis()

Returns stream of subsets whose traitset satisfies current subset's traitset.

getSatisfyingSubsets

@API(since="1.23",
     status=EXPERIMENTAL)
public Stream<RelSubset> getSatisfyingSubsets()

Returns stream of subsets whose traitset is satisfied by current subset's traitset.

getWinnerCost

@API(since="1.24",
     status=INTERNAL)
public RelOptCost getWinnerCost()

Returns the best cost if this subset is fully optimized or null if the subset is not fully optimized.

getDigest

public String getDigest()

Description copied from interface: RelNode

Returns a digest string of this RelNode.

Each call creates a new digest string, so don't forget to cache the result if necessary.

Specified by:

getDigest in interface RelOptNode

Specified by:

getDigest in interface RelNode

Overrides:

getDigest in class AbstractRelNode

Returns:

Digest string of this RelNode

See Also:

RelNode.getRelDigest()