Package org.apache.druid.segment.join

Class MapJoinableFactory

java.lang.Object

org.apache.druid.segment.join.MapJoinableFactory

All Implemented Interfaces:

JoinableFactory

public class MapJoinableFactory
extends Object
implements JoinableFactory

A JoinableFactory that delegates to the appropriate factory based on the datasource. Any number of JoinableFactory may be associated to the same class of DataSource, but for a specific datasource only a single JoinableFactory should be able to create a Joinable in the build(org.apache.druid.query.DataSource, org.apache.druid.segment.join.JoinConditionAnalysis) method.

Constructor Summary

Constructors

Constructor	Description
MapJoinableFactory(Set<JoinableFactory> factories, Map<Class<? extends JoinableFactory>,Class<? extends DataSource>> factoryToDataSource)

Method Summary

Modifier and Type	Method	Description
Optional<Joinable>	build(DataSource dataSource, JoinConditionAnalysis condition)	Create a Joinable object.
Optional<byte[]>	computeJoinCacheKey(DataSource dataSource, JoinConditionAnalysis condition)	Compute the cache key for a data source participating in join operation.
boolean	isDirectlyJoinable(DataSource dataSource)	Returns true if a Joinable **may** be created for a given DataSource, but is not a guarantee that JoinableFactory.build(org.apache.druid.query.DataSource, org.apache.druid.segment.join.JoinConditionAnalysis) will return a non-empty result.

Methods inherited from class java.lang.Object

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

Constructor Detail

MapJoinableFactory

@Inject
public MapJoinableFactory(Set<JoinableFactory> factories,
                          Map<Class<? extends JoinableFactory>,Class<? extends DataSource>> factoryToDataSource)

Method Detail

isDirectlyJoinable

public boolean isDirectlyJoinable(DataSource dataSource)

Description copied from interface: JoinableFactory

Returns true if a Joinable **may** be created for a given DataSource, but is not a guarantee that JoinableFactory.build(org.apache.druid.query.DataSource, org.apache.druid.segment.join.JoinConditionAnalysis) will return a non-empty result. Successfully building a Joinable might require specific criteria of the JoinConditionAnalysis.

Specified by:

isDirectlyJoinable in interface JoinableFactory

build

public Optional<Joinable> build(DataSource dataSource,
                                JoinConditionAnalysis condition)

Description copied from interface: JoinableFactory

Create a Joinable object. This may be an expensive operation involving loading data, creating a hash table, etc.

Specified by:

build in interface JoinableFactory

Parameters:

dataSource - the datasource to join on

condition - the condition to join on

Returns:

a Joinable if this datasource + condition combo is joinable; empty if not

computeJoinCacheKey

public Optional<byte[]> computeJoinCacheKey(DataSource dataSource,
                                            JoinConditionAnalysis condition)

Description copied from interface: JoinableFactory

Compute the cache key for a data source participating in join operation. This is done separately from {JoinableFactory.build(DataSource, JoinConditionAnalysis)} which can be an expensive operation and can potentially be avoided if cached results can be used.

Specified by:

computeJoinCacheKey in interface JoinableFactory

Parameters:

dataSource - the datasource to join on

condition - the condition to join on