Package org.apache.calcite.plan.volcano

Class AbstractConverter

java.lang.Object

org.apache.calcite.rel.AbstractRelNode

org.apache.calcite.rel.SingleRel

org.apache.calcite.rel.convert.ConverterImpl

org.apache.calcite.plan.volcano.AbstractConverter

All Implemented Interfaces:

Cloneable, RelOptNode, Converter, RelNode

@Enclosing
public class AbstractConverter
extends ConverterImpl

Converts a relational expression to any given output convention.

Unlike most Converters, an abstract converter is always abstract. You would typically create an AbstractConverter when it is necessary to transform a relational expression immediately; later, rules will transform it into relational expressions which can be implemented.

If an abstract converter cannot be satisfied immediately (because the source subset is abstract), the set is flagged, so this converter will be expanded as soon as a non-abstract relexp is added to the set.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	AbstractConverter.ExpandConversionRule	Rule that converts an AbstractConverter into a chain of converters from the source relation to the target traits.

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

RelNode.Context

Field Summary

Fields inherited from class org.apache.calcite.rel.convert.ConverterImpl

inTraits, traitDef

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

input

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

digest, id, rowType, traitSet

Constructor Summary

Constructors

Constructor	Description
AbstractConverter(RelOptCluster cluster, RelSubset rel, @Nullable RelTraitDef traitDef, RelTraitSet traits)

Method Summary

Modifier and Type	Method	Description
@Nullable 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.
RelWriter	explainTerms(RelWriter pw)	Describes the inputs and attributes of this relational expression.
boolean	isEnforcer()	Indicates whether it is an enforcer operator, e.g.

Methods inherited from class org.apache.calcite.rel.convert.ConverterImpl

cannotImplement, getInputTraits, getTraitDef

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

childrenAccept, deriveRowType, estimateRowCount, getInput, getInputs, replaceInput

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

accept, accept, collectVariablesSet, collectVariablesUsed, deepEquals, deepHashCode, equals, explain, getCluster, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getRelDigest, getRelTypeName, getRowType, getTable, getTraitSet, getVariablesSet, hashCode, 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.convert.Converter

getInput

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

accept, accept, childrenAccept, collectVariablesSet, collectVariablesUsed, deepEquals, deepHashCode, estimateRowCount, explain, explain, fieldIsNullable, getConvention, getCorrelVariable, getDigest, getExpectedInputRowType, getInput, getInputs, getRelDigest, getRelTypeName, getRowType, getTable, getVariablesSet, isValid, metadata, onRegister, recomputeDigest, register, replaceInput, stripped

Methods inherited from interface org.apache.calcite.plan.RelOptNode

getCluster, getDescription, getId, getTraitSet

Constructor Details

AbstractConverter

public AbstractConverter(RelOptCluster cluster,
 RelSubset rel,
 @Nullable RelTraitDef traitDef,
 RelTraitSet traits)

Method Details

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 @Nullable 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 ConverterImpl

Parameters:

planner - Planner for cost calculation

mq - Metadata query

Returns:

Cost of this plan (not including children)

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

Overrides:

explainTerms in class SingleRel

Parameters:

pw - Plan writer

Returns:

Plan writer for fluent-explain pattern

isEnforcer

public boolean isEnforcer()

Description copied from interface: RelNode

Indicates whether it is an enforcer operator, e.g. PhysicalSort, PhysicalHashDistribute, etc. As an enforcer, the operator must be created only when required traitSet is not satisfied by its input.

Specified by:

isEnforcer in interface RelNode

Overrides:

isEnforcer in class AbstractRelNode

Returns:

Whether it is an enforcer operator