MetadataFactoryImpl (Apache Calcite API)

java.lang.Object
- org.apache.calcite.rel.metadata.MetadataFactoryImpl

All Implemented Interfaces:

MetadataFactory
```
public class MetadataFactoryImpl
extends java.lang.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	Description
`private com.google.common.cache.LoadingCache<Pair<java.lang.Class<RelNode>,java.lang.Class<Metadata>>,UnboundMetadata<Metadata>>`	`cache`
`static UnboundMetadata<Metadata>`	`DUMMY`

Constructor Summary

Constructors
Constructor Description

MetadataFactoryImpl(RelMetadataProvider provider)

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`private static com.google.common.cache.CacheLoader<Pair<java.lang.Class<RelNode>,java.lang.Class<Metadata>>,UnboundMetadata<Metadata>>`	`loader(RelMetadataProvider provider)`
`<M extends Metadata> M`	`query(RelNode rel, RelMetadataQuery mq, java.lang.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<java.lang.Class<RelNode>,java.lang.Class<Metadata>>,UnboundMetadata<Metadata>> cache

Constructor Detail

MetadataFactoryImpl

public MetadataFactoryImpl(RelMetadataProvider provider)

Method Detail
- loader
```
private static com.google.common.cache.CacheLoader<Pair<java.lang.Class<RelNode>,java.lang.Class<Metadata>>,UnboundMetadata<Metadata>> loader(RelMetadataProvider provider)
```
- query
```
public <M extends Metadata> M query(RelNode rel,
                                    RelMetadataQuery mq,
                                    java.lang.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