org.apache.calcite.rel.metadata

Class CachingRelMetadataProvider

java.lang.Object

org.apache.calcite.rel.metadata.CachingRelMetadataProvider

All Implemented Interfaces:

RelMetadataProvider

public class CachingRelMetadataProvider
extends Object
implements RelMetadataProvider

Implementation of the RelMetadataProvider interface that caches results from an underlying provider.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	CachingRelMetadataProvider.CacheEntry An entry in the cache.
private class	CachingRelMetadataProvider.CachingInvocationHandler Implementation of InvocationHandler for calls to a CachingRelMetadataProvider.

Field Summary

Fields

Modifier and Type	Field and Description
private Map<List,CachingRelMetadataProvider.CacheEntry>	cache
private RelOptPlanner	planner
private RelMetadataProvider	underlyingProvider

Constructor Summary

Constructors

Constructor and Description
CachingRelMetadataProvider(RelMetadataProvider underlyingProvider, RelOptPlanner planner)

Method Summary

Modifier and Type	Method and Description
<M extends Metadata> UnboundMetadata<M>	apply(Class<? extends RelNode> relClass, Class<? extends M> metadataClass) Retrieves metadata of a particular type and for a particular sub-class of relational expression.
<M extends Metadata> com.google.common.collect.Multimap<Method,MetadataHandler<M>>	handlers(MetadataDef<M> def)

Methods inherited from class java.lang.Object

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

Field Detail

cache

private final Map<List,CachingRelMetadataProvider.CacheEntry> cache

underlyingProvider

private final RelMetadataProvider underlyingProvider

planner

private final RelOptPlanner planner

Constructor Detail

CachingRelMetadataProvider

public CachingRelMetadataProvider(RelMetadataProvider underlyingProvider,
                                  RelOptPlanner planner)

Method Detail

apply

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

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

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

Specified by:

handlers in interface RelMetadataProvider