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

Methods inherited from class java.lang.Object

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

Constructor Details

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 Details

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

Deprecated.