org.apache.calcite.rel.metadata

Class MetadataFactoryImpl

java.lang.Object

org.apache.calcite.rel.metadata.MetadataFactoryImpl

All Implemented Interfaces:

MetadataFactory

public class MetadataFactoryImpl
extends Object
implements MetadataFactory

Implementation of MetadataFactory that gets providers from a RelMetadataProvider and stores them in a cache.

The cache does not store metadata. It remembers which providers can provide which kinds of metadata, for which kinds of relational expressions.

Field Summary

Fields

Modifier and Type	Field and Description
private com.google.common.cache.LoadingCache<Pair<Class<RelNode>,Class<Metadata>>,UnboundMetadata<Metadata>>	cache
static UnboundMetadata<Metadata>	DUMMY

Constructor Summary

Constructors

Constructor and Description
MetadataFactoryImpl(RelMetadataProvider provider)

Method Summary

Modifier and Type	Method and Description
private static com.google.common.cache.CacheLoader<Pair<Class<RelNode>,Class<Metadata>>,UnboundMetadata<Metadata>>	loader(RelMetadataProvider provider)
<M extends Metadata> M	query(RelNode rel, RelMetadataQuery mq, Class<M> metadataClazz) Returns a metadata interface to get a particular kind of metadata from a particular relational expression.

Methods inherited from class java.lang.Object

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

Field Detail

DUMMY

public static final UnboundMetadata<Metadata> DUMMY

cache

private final com.google.common.cache.LoadingCache<Pair<Class<RelNode>,Class<Metadata>>,UnboundMetadata<Metadata>> cache

Constructor Detail

MetadataFactoryImpl

public MetadataFactoryImpl(RelMetadataProvider provider)

Method Detail

loader

private static com.google.common.cache.CacheLoader<Pair<Class<RelNode>,Class<Metadata>>,UnboundMetadata<Metadata>> loader(RelMetadataProvider provider)

query

public <M extends Metadata> M query(RelNode rel,
                                    RelMetadataQuery mq,
                                    Class<M> metadataClazz)

Description copied from interface: MetadataFactory

Returns a metadata interface to get a particular kind of metadata from a particular relational expression. Returns null if that kind of metadata is not available.

Specified by:

query in interface MetadataFactory

Type Parameters:

M - Metadata type

Parameters:

rel - Relational expression

mq - Metadata query

metadataClazz - Metadata class

Returns:

Metadata bound to rel and query