org.apache.calcite.rel.metadata

Class ReflectiveRelMetadataProvider

java.lang.Object

org.apache.calcite.rel.metadata.ReflectiveRelMetadataProvider

All Implemented Interfaces:

RelMetadataProvider, ReflectiveVisitor

public class ReflectiveRelMetadataProvider
extends Object
implements RelMetadataProvider, ReflectiveVisitor

Implementation of the RelMetadataProvider interface that dispatches metadata methods to methods on a given object via reflection.

The methods on the target object must be public and non-static, and have the same signature as the implemented metadata method except for an additional first parameter of type RelNode or a sub-class. That parameter gives this provider an indication of that relational expressions it can handle.

For an example, see RelMdColumnOrigins.SOURCE.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ReflectiveRelMetadataProvider(ConcurrentMap<Class<RelNode>,UnboundMetadata> map, Class<? extends Metadata> metadataClass0, com.google.common.collect.Multimap<Method,MetadataHandler<?>> handlerMap, Class<? extends MetadataHandler<?>> handlerClass) Creates a ReflectiveRelMetadataProvider.

Method Summary

Modifier and Type	Method and Description
<M extends Metadata> @Nullable UnboundMetadata<M>	apply(Class<? extends RelNode> relClass) Deprecated.
<M extends Metadata> @Nullable UnboundMetadata<M>	apply(Class<? extends RelNode> relClass, Class<? extends M> metadataClass) Deprecated.
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.
static <M extends Metadata> RelMetadataProvider	reflectiveSource(MetadataHandler<? extends M> handler, Class<? extends MetadataHandler<M>> handlerClass)
static RelMetadataProvider	reflectiveSource(MetadataHandler target, Method... methods) Deprecated.
static RelMetadataProvider	reflectiveSource(Method method, MetadataHandler target) Deprecated.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReflectiveRelMetadataProvider

protected ReflectiveRelMetadataProvider(ConcurrentMap<Class<RelNode>,UnboundMetadata> map,
                                        Class<? extends Metadata> metadataClass0,
                                        com.google.common.collect.Multimap<Method,MetadataHandler<?>> handlerMap,
                                        Class<? extends MetadataHandler<?>> handlerClass)

Creates a ReflectiveRelMetadataProvider.

Parameters:

map - Map

metadataClass0 - Metadata class

handlerMap - Methods handled and the objects to call them on

Method Detail

reflectiveSource

@Deprecated
public static RelMetadataProvider reflectiveSource(Method method,
                                                               MetadataHandler target)

Deprecated.

Returns an implementation of RelMetadataProvider that scans for methods with a preceding argument.

For example, BuiltInMetadata.Selectivity has a method BuiltInMetadata.Selectivity.getSelectivity(RexNode). A class

 class RelMdSelectivity {
   public Double getSelectivity(Union rel, RexNode predicate) { }
   public Double getSelectivity(Filter rel, RexNode predicate) { }
 

provides implementations of selectivity for relational expressions that extend Union or Filter.

reflectiveSource

@Deprecated
public static RelMetadataProvider reflectiveSource(MetadataHandler target,
                                                               Method... methods)

Deprecated.

Returns a reflective metadata provider that implements several methods.

reflectiveSource

public static <M extends Metadata> RelMetadataProvider reflectiveSource(MetadataHandler<? extends M> handler,
                                                                        Class<? extends MetadataHandler<M>> handlerClass)

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

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

apply

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

Deprecated.