org.apache.calcite.rel

Class AbstractRelNode

java.lang.Object

org.apache.calcite.rel.AbstractRelNode

All Implemented Interfaces:

Cloneable, RelOptNode, RelNode

Direct Known Subclasses:

BiRel, HepRelVertex, MultiJoin, RelSubset, SetOp, SingleRel, TableFunctionScan, TableScan, Values

public abstract class AbstractRelNode
extends Object
implements RelNode

Base class for every relational expression (RelNode).

Field Summary

Fields

Modifier and Type	Field and Description
protected String	digest A short description of this relational expression's type, inputs, and other properties.
protected int	id unique id of this object -- for debugging
protected RelDataType	rowType Cached type of this relational expression.
protected RelTraitSet	traitSet The RelTraitSet that describes the traits of this RelNode.

Constructor Summary

Constructors

Constructor and Description
AbstractRelNode(RelOptCluster cluster, RelTraitSet traitSet) Creates an AbstractRelNode.

Method Summary

Methods

Modifier and Type	Method and Description
RelNode	accept(RelShuttle shuttle) Accepts a visit from a shuttle.
RelNode	accept(RexShuttle shuttle) Accepts a visit from a shuttle.
void	childrenAccept(RelVisitor visitor) Interacts with the RelVisitor in a visitor pattern to traverse the tree of relational expressions.
void	collectVariablesSet(Set<String> variableSet) Collects variables set by this expression.
void	collectVariablesUsed(Set<String> variableSet) Collects variables known to be used by this expression or its descendants.
protected String	computeDigest() Computes the digest.
RelOptCost	computeSelfCost(RelOptPlanner planner) 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.
protected RelDataType	deriveRowType()
void	explain(RelWriter pw) Describes the inputs and attributes of this relational expression.
RelWriter	explainTerms(RelWriter pw) Describes the inputs and attributes of this relational expression.
List<RexNode>	getChildExps() Returns a list of this relational expression's child expressions.
RelOptCluster	getCluster() Returns the cluster this relational expression belongs to.
List<RelCollation>	getCollationList() Deprecated. Use RelMetadataQuery.collations(RelNode)
Convention	getConvention() Return the CallingConvention trait from this RelNode's trait set.
String	getCorrelVariable() Returns the name of the variable which is to be implicitly set at runtime each time a row is returned from the first input of this relational expression; or null if there is no variable.
String	getDescription() Returns a string which describes the relational expression and, unlike RelOptNode.getDigest(), also includes the identity.
String	getDigest() Returns a string which concisely describes the definition of this relational expression.
RelDataType	getExpectedInputRowType(int ordinalInParent) Returns the type of the rows expected for an input.
int	getId() Returns the ID of this relational expression, unique among all relational expressions created since the server was started.
RelNode	getInput(int i) Returns the ith input relational expression.
List<RelNode>	getInputs() Returns an array of this relational expression's inputs.
RelOptQuery	getQuery() Returns the sub-query this relational expression belongs to.
String	getRelTypeName() Returns the name of this relational expression's class, sans package name, for use in explain.
double	getRows() Returns an estimate of the number of rows this relational expression will return.
RelDataType	getRowType() Returns the type of the rows returned by this relational expression.
RelOptTable	getTable() If this relational expression represents an access to a table, returns that table, otherwise returns null.
RelTraitSet	getTraitSet() Retrieves this RelNode's traits.
Set<String>	getVariablesStopped() Returns the names of variables which are set in this relational expression but also used and therefore not available to parents of this relational expression.
boolean	isDistinct() Returns whether the same value will not come out twice.
boolean	isKey(ImmutableBitSet columns) Returns whether the result of this relational expression is uniquely identified by this columns with the given ordinals.
boolean	isValid(boolean fail) Returns whether this relational expression is valid.
<M extends Metadata> M	metadata(Class<M> metadataClass) Returns a metadata interface.
RelNode	onRegister(RelOptPlanner planner) Receives notification that this expression is about to be registered.
String	recomputeDigest() Computes the digest, assigns it, and returns it.
void	register(RelOptPlanner planner) Registers any special rules specific to this kind of relational expression.
void	replaceInput(int ordinalInParent, RelNode p) Replaces the ordinalInParentth input.
protected static <T> T	sole(List<T> collection)
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

rowType

protected RelDataType rowType

Cached type of this relational expression.

digest

protected String digest

A short description of this relational expression's type, inputs, and other properties. The string uniquely identifies the node; another node is equivalent if and only if it has the same value. Computed by computeDigest(), assigned by onRegister(org.apache.calcite.plan.RelOptPlanner), returned by getDigest().

See Also:

desc

id

protected int id

unique id of this object -- for debugging

traitSet

protected RelTraitSet traitSet

The RelTraitSet that describes the traits of this RelNode.

Constructor Detail

AbstractRelNode

public AbstractRelNode(RelOptCluster cluster,
               RelTraitSet traitSet)

Creates an AbstractRelNode.

Method Detail

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

Parameters:

traitSet - Trait set

inputs - Inputs

Returns:

Copy of this relational expression, substituting traits and inputs

sole

protected static <T> T sole(List<T> collection)

getChildExps

public List<RexNode> getChildExps()

Description copied from interface: RelNode

Returns a list of this relational expression's child expressions. (These are scalar expressions, and so do not include the relational inputs that are returned by RelNode.getInputs().

The caller should treat the list as unmodifiable; typical implementations will return an immutable list. If there are no child expressions, returns an empty list, not null.

Specified by:

getChildExps in interface RelNode

Returns:

List of this relational expression's child expressions

See Also:

RelNode.accept(org.apache.calcite.rex.RexShuttle)

getCluster

public final RelOptCluster getCluster()

Description copied from interface: RelOptNode

Returns the cluster this relational expression belongs to.

Specified by:

getCluster in interface RelOptNode

Returns:

cluster

getConvention

public final Convention getConvention()

Description copied from interface: RelNode

Return the CallingConvention trait from this RelNode's trait set.

Specified by:

getConvention in interface RelNode

Returns:

this RelNode's CallingConvention

getTraitSet

public RelTraitSet getTraitSet()

Description copied from interface: RelOptNode

Retrieves this RelNode's traits. Note that although the RelTraitSet returned is modifiable, it must not be modified during optimization. It is legal to modify the traits of a RelNode before or after optimization, although doing so could render a tree of RelNodes unimplementable. If a RelNode's traits need to be modified during optimization, clone the RelNode and change the clone's traits.

Specified by:

getTraitSet in interface RelOptNode

Returns:

this RelNode's trait set

getCorrelVariable

public String getCorrelVariable()

Description copied from interface: RelNode

Returns the name of the variable which is to be implicitly set at runtime each time a row is returned from the first input of this relational expression; or null if there is no variable.

Specified by:

getCorrelVariable in interface RelNode

Returns:

Name of correlating variable, or null

isDistinct

public boolean isDistinct()

Description copied from interface: RelNode

Returns whether the same value will not come out twice. Default value is false, derived classes should override.

Specified by:

isDistinct in interface RelNode

Returns:

Whether the same value will not come out twice

isKey

public boolean isKey(ImmutableBitSet columns)

Description copied from interface: RelNode

Returns whether the result of this relational expression is uniquely identified by this columns with the given ordinals.

For example, if this relational expression is a LogicalTableScan to T(A, B, C, D) whose key is (A, B), then isKey([0, 1]) yields true, and isKey([0]) and isKey([0, 2]) yields false.

Specified by:

isKey in interface RelNode

Parameters:

columns - Ordinals of key columns

Returns:

Whether the given columns are a key or a superset of a key

getId

public int getId()

Description copied from interface: RelOptNode

Returns the ID of this relational expression, unique among all relational expressions created since the server was started.

Specified by:

getId in interface RelOptNode

Returns:

Unique ID

getInput

public RelNode getInput(int i)

Description copied from interface: RelNode

Returns the i^th input relational expression.

Specified by:

getInput in interface RelNode

Parameters:

i - Ordinal of input

Returns:

i^th input

getQuery

public final RelOptQuery getQuery()

Description copied from interface: RelNode

Returns the sub-query this relational expression belongs to.

Specified by:

getQuery in interface RelNode

Returns:

Sub-query

register

public void register(RelOptPlanner planner)

Description copied from interface: RelNode

Registers any special rules specific to this kind of relational expression.

The planner calls this method this first time that it sees a relational expression of this class. The derived class should call RelOptPlanner.addRule(org.apache.calcite.plan.RelOptRule) for each rule, and then call super.register.

Specified by:

register in interface RelNode

Parameters:

planner - Planner to be used to register additional relational expressions

getRelTypeName

public final String getRelTypeName()

Description copied from interface: RelNode

Returns the name of this relational expression's class, sans package name, for use in explain. For example, for a org.apache.calcite.rel.ArrayRel.ArrayReader, this method returns "ArrayReader".

Specified by:

getRelTypeName in interface RelNode

Returns:

Name of this relational expression's class, sans package name, for use in explain

isValid

public boolean isValid(boolean fail)

Description copied from interface: RelNode

Returns whether this relational expression is valid.

If assertions are enabled, this method is typically called with fail = true, as follows:

assert rel.isValid(true)

This signals that the method can throw an AssertionError if it is not valid.

Specified by:

isValid in interface RelNode

Parameters:

fail - Whether to fail if invalid

Returns:

Whether relational expression is valid

getCollationList

@Deprecated
public List<RelCollation> getCollationList()

Deprecated. Use RelMetadataQuery.collations(RelNode)

Description copied from interface: RelNode

Returns a description of the physical ordering (or orderings) of this relational expression. Never null.

Specified by:

getCollationList in interface RelNode

Returns:

Description of the physical ordering (or orderings) of this relational expression. Never null

getRowType

public final RelDataType getRowType()

Description copied from interface: RelNode

Returns the type of the rows returned by this relational expression.

Specified by:

getRowType in interface RelOptNode

Specified by:

getRowType in interface RelNode

deriveRowType

protected RelDataType deriveRowType()

getExpectedInputRowType

public RelDataType getExpectedInputRowType(int ordinalInParent)

Description copied from interface: RelNode

Returns the type of the rows expected for an input. Defaults to RelNode.getRowType().

Specified by:

getExpectedInputRowType in interface RelNode

Parameters:

ordinalInParent - input's 0-based ordinal with respect to this parent rel

Returns:

expected row type

getInputs

public List<RelNode> getInputs()

Description copied from interface: RelNode

Returns an array of this relational expression's inputs. If there are no inputs, returns an empty list, not null.

Specified by:

getInputs in interface RelOptNode

Specified by:

getInputs in interface RelNode

Returns:

Array of this relational expression's inputs

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

Returns:

Estimate of the number of rows this relational expression will return

getVariablesStopped

public Set<String> getVariablesStopped()

Description copied from interface: RelNode

Returns the names of variables which are set in this relational expression but also used and therefore not available to parents of this relational expression.

Note: only Correlate should set variables

Specified by:

getVariablesStopped in interface RelNode

Returns:

Names of variables which are set in this relational expression

collectVariablesUsed

public void collectVariablesUsed(Set<String> 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

Parameters:

variableSet - receives variables used

collectVariablesSet

public void collectVariablesSet(Set<String> variableSet)

Description copied from interface: RelNode

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

Specified by:

collectVariablesSet in interface RelNode

Parameters:

variableSet - receives variables known to be set by

childrenAccept

public void childrenAccept(RelVisitor visitor)

Description copied from interface: RelNode

Interacts with the RelVisitor in a visitor pattern to traverse the tree of relational expressions.

Specified by:

childrenAccept in interface RelNode

Parameters:

visitor - Visitor that will traverse the tree of relational expressions

accept

public RelNode accept(RelShuttle shuttle)

Description copied from interface: RelNode

Accepts a visit from a shuttle.

Specified by:

accept in interface RelNode

Parameters:

shuttle - Shuttle

Returns:

A copy of this node incorporating changes made by the shuttle to this node's children

accept

public RelNode accept(RexShuttle shuttle)

Description copied from interface: RelNode

Accepts a visit from a shuttle. If the shuttle updates expression, then a copy of the relation should be created.

Specified by:

accept in interface RelNode

Parameters:

shuttle - Shuttle

Returns:

A copy of this node incorporating changes made by the shuttle to this node's children

computeSelfCost

public RelOptCost computeSelfCost(RelOptPlanner planner)

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

Parameters:

planner - Planner for cost calculation

Returns:

Cost of this plan (not including children)

metadata

public final <M extends Metadata> M metadata(Class<M> metadataClass)

Description copied from interface: RelNode

Returns a metadata interface.

Specified by:

metadata in interface RelNode

Type Parameters:

M - Type of metadata being requested

Parameters:

metadataClass - Metadata interface

Returns:

Metadata object that supplies the desired metadata (never null, although if the information is not present the metadata object may return null from all methods)

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 RelWriterImpl.input(String, RelNode) and RelWriterImpl.item(String, Object) methods for each input and attribute.

Specified by:

explain in interface RelNode

Parameters:

pw - Plan writer

explainTerms

public RelWriter explainTerms(RelWriter pw)

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

Parameters:

pw - Plan writer

Returns:

Plan writer for fluent-explain pattern

onRegister

public RelNode onRegister(RelOptPlanner planner)

Description copied from interface: RelNode

Receives notification that this expression is about to be registered. The implementation of this method must at least register all child expressions.

Specified by:

onRegister in interface RelNode

Parameters:

planner - Planner that plans this relational node

Returns:

Relational expression that should be used by the planner

recomputeDigest

public String recomputeDigest()

Description copied from interface: RelNode

Computes the digest, assigns it, and returns it. For planner use only.

Specified by:

recomputeDigest in interface RelNode

Returns:

Digest of this relational expression

replaceInput

public void replaceInput(int ordinalInParent,
                RelNode p)

Description copied from interface: RelNode

Replaces the ordinalInParent^th input. You must override this method if you override RelNode.getInputs().

Specified by:

replaceInput in interface RelNode

Parameters:

ordinalInParent - Position of the child input, 0 is the first

p - New node that should be put at position ordinalInParent

toString

public String toString()

Overrides:

toString in class Object

getDescription

public final String getDescription()

Description copied from interface: RelOptNode

Returns a string which describes the relational expression and, unlike RelOptNode.getDigest(), also includes the identity. Typically returns "rel#{id}:{digest}".

Specified by:

getDescription in interface RelOptNode

Returns:

String which describes the relational expression and, unlike RelOptNode.getDigest(), also includes the identity

getDigest

public final String getDigest()

Description copied from interface: RelOptNode

Returns a string which concisely describes the definition of this relational expression. Two relational expressions are equivalent if and only if their digests are the same.

The digest does not contain the relational expression's identity -- that would prevent similar relational expressions from ever comparing equal -- but does include the identity of children (on the assumption that children have already been normalized).

If you want a descriptive string which contains the identity, call Object.toString(), which always returns "rel#{id}:{digest}".

Specified by:

getDigest in interface RelOptNode

Returns:

Digest of this RelNode

getTable

public RelOptTable getTable()

Description copied from interface: RelNode

If this relational expression represents an access to a table, returns that table, otherwise returns null.

Specified by:

getTable in interface RelNode

Returns:

If this relational expression represents an access to a table, returns that table, otherwise returns null

computeDigest

protected String computeDigest()

Computes the digest. Does not modify this object.

Returns:

Digest