Package org.apache.druid.segment.join

Class HashJoinSegment

java.lang.Object

org.apache.druid.segment.join.HashJoinSegment

All Implemented Interfaces:

Closeable, AutoCloseable, ReferenceCountedObject, Segment, SegmentReference

public class HashJoinSegment
extends Object
implements SegmentReference

Represents a deep, left-heavy join of a left-hand side baseSegment onto a series of right-hand side clauses.

In other words, logically the operation is: join(join(join(baseSegment, clauses[0]), clauses[1]), clauses[2]) etc.

Constructor Summary

Constructors

Constructor	Description
HashJoinSegment(SegmentReference baseSegment, Filter baseFilter, List<JoinableClause> clauses, JoinFilterPreAnalysis joinFilterPreAnalysis)

Method Summary

Modifier and Type	Method	Description
Optional<Closeable>	acquireReferences()	This method is expected to increment a reference count and provide a Closeable that decrements the reference count when closed.
<T> T	as(Class<T> clazz)	Request an implementation of a particular interface.
QueryableIndex	asQueryableIndex()
StorageAdapter	asStorageAdapter()
void	close()
org.joda.time.Interval	getDataInterval()
SegmentId	getId()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.druid.segment.Segment

asString

Constructor Detail

HashJoinSegment

public HashJoinSegment(SegmentReference baseSegment,
                       @Nullable
                       Filter baseFilter,
                       List<JoinableClause> clauses,
                       JoinFilterPreAnalysis joinFilterPreAnalysis)

Parameters:

baseSegment - The left-hand side base segment

clauses - The right-hand side clauses. The caller is responsible for ensuring that there are no duplicate prefixes or prefixes that shadow each other across the clauses

joinFilterPreAnalysis - Pre-analysis for the query we expect to run on this segment

Method Detail

getId

public SegmentId getId()

Specified by:

getId in interface Segment

getDataInterval

public org.joda.time.Interval getDataInterval()

Specified by:

getDataInterval in interface Segment

asQueryableIndex

@Nullable
public QueryableIndex asQueryableIndex()

Specified by:

asQueryableIndex in interface Segment

asStorageAdapter

public StorageAdapter asStorageAdapter()

Specified by:

asStorageAdapter in interface Segment

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

acquireReferences

public Optional<Closeable> acquireReferences()

Description copied from interface: ReferenceCountedObject

This method is expected to increment a reference count and provide a Closeable that decrements the reference count when closed. This is likely just a wrapper around ReferenceCountingCloseableObject.incrementReferenceAndDecrementOnceCloseable(), but may also include any other associated references which should be incremented when this method is called, and decremented/released by the closeable. IMPORTANT NOTE: to fulfill the contract of this method, implementors must return a closeable to indicate that the reference can be acquired, even if there is nothing to close. Implementors should avoid allowing this method or the Closeable it creates to throw exceptions. For callers: if this method returns non-empty, IT MUST BE CLOSED, else reference counts can potentially leak.

Specified by:

acquireReferences in interface ReferenceCountedObject

as

public <T> T as(Class<T> clazz)

Description copied from interface: Segment

Request an implementation of a particular interface. If the passed-in interface is QueryableIndex or StorageAdapter, then this method behaves identically to Segment.asQueryableIndex() or Segment.asStorageAdapter(). Other interfaces are only expected to be requested by callers that have specific knowledge of extra features provided by specific segment types. For example, an extension might provide a custom Segment type that can offer both StorageAdapter and some new interface. That extension can also offer a Query that uses that new interface. Implementations which accept classes other than QueryableIndex or StorageAdapter are limited to using those classes within the extension. This means that one extension cannot rely on the `Segment.as` behavior of another extension.

Specified by:

as in interface Segment

Type Parameters:

T - desired interface

Parameters:

clazz - desired interface

Returns:

instance of clazz, or null if the interface is not supported by this segment