org.apache.calcite.rel.metadata

Class ChainedRelMetadataProvider

java.lang.Object

org.apache.calcite.rel.metadata.ChainedRelMetadataProvider

All Implemented Interfaces:

RelMetadataProvider

Direct Known Subclasses:

DefaultRelMetadataProvider

public class ChainedRelMetadataProvider
extends Object
implements RelMetadataProvider

Implementation of the RelMetadataProvider interface via the Glossary.CHAIN_OF_RESPONSIBILITY_PATTERN.

When a consumer calls the apply(java.lang.Class<? extends org.apache.calcite.rel.RelNode>, java.lang.Class<? extends M>) method to ask for a provider for a particular type of RelNode and Metadata, scans the list of underlying providers.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ChainedRelMetadataProvider(com.google.common.collect.ImmutableList<RelMetadataProvider> providers) Creates a chain.

Method Summary

Modifier and Type	Method and Description
<M extends Metadata> @Nullable UnboundMetadata<M>	apply(Class<? extends RelNode> relClass, Class<? extends M> metadataClass) Deprecated.
boolean	equals(@Nullable Object obj)
List<MetadataHandler<?>>	handlers(Class<? extends MetadataHandler<?>> handlerClass) Retrieves a list of MetadataHandler for implements a particular MetadataHandler.class.
<M extends Metadata> com.google.common.collect.Multimap<Method,MetadataHandler<M>>	handlers(MetadataDef<M> def) Deprecated.
int	hashCode()
static RelMetadataProvider	of(List<RelMetadataProvider> list) Creates a chain.

Methods inherited from class java.lang.Object

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

Constructor Detail

ChainedRelMetadataProvider

protected ChainedRelMetadataProvider(com.google.common.collect.ImmutableList<RelMetadataProvider> providers)

Creates a chain.

Method Detail

equals

public boolean equals(@Nullable Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

apply

@Deprecated
public <M extends Metadata> @Nullable UnboundMetadata<M> apply(Class<? extends RelNode> relClass,
                                                                           Class<? extends M> metadataClass)

Deprecated.

Description copied from interface: RelMetadataProvider

Retrieves metadata of a particular type and for a particular sub-class of relational expression.

The object returned is a function. It can be applied to a relational expression of the given type to create a metadata object.

For example, you might call

 RelMetadataProvider provider;
 LogicalFilter filter;
 RexNode predicate;
 Function<RelNode, Metadata> function =
   provider.apply(LogicalFilter.class, Selectivity.class};
 Selectivity selectivity = function.apply(filter);
 Double d = selectivity.selectivity(predicate);
 

Specified by:

apply in interface RelMetadataProvider

Parameters:

relClass - Type of relational expression

metadataClass - Type of metadata

Returns:

Function that will field a metadata instance; or null if this provider cannot supply metadata of this type

handlers

@Deprecated
public <M extends Metadata> com.google.common.collect.Multimap<Method,MetadataHandler<M>> handlers(MetadataDef<M> def)

Deprecated.

Specified by:

handlers in interface RelMetadataProvider

handlers

public List<MetadataHandler<?>> handlers(Class<? extends MetadataHandler<?>> handlerClass)

Description copied from interface: RelMetadataProvider

Retrieves a list of MetadataHandler for implements a particular MetadataHandler.class. The resolution order is specificity of the relNode class, with preference given to handlers that occur earlier in the list. For instance, given a return list of {A, B, C} where A implements RelNode and Scan, B implements Scan, and C implements LogicalScan and Filter. Scan dispatches to a.method(Scan) LogicalFilter dispatches to c.method(Filter). LogicalScan dispatches to c.method(LogicalScan). Aggregate dispatches to a.method(RelNode). The behavior is undefined if the class hierarchy for dispatching is not a tree.

Specified by:

handlers in interface RelMetadataProvider

of

public static RelMetadataProvider of(List<RelMetadataProvider> list)

Creates a chain.