Package org.apache.druid.segment.join

Class HashJoinSegment

java.lang.Object

org.apache.druid.segment.join.HashJoinSegment

All Implemented Interfaces:

Closeable, AutoCloseable, Segment

public class HashJoinSegment
extends Object
implements Segment

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(Segment baseSegment, Filter baseFilter, List<JoinableClause> clauses, JoinFilterPreAnalysis joinFilterPreAnalysis, Closeable referenceCloseable)

Method Summary

Modifier and Type	Method	Description
<T> T	as(Class<T> clazz)	Request an implementation of a particular interface.
void	close()
org.joda.time.Interval	getDataInterval()
String	getDebugString()	Developer friendly string suitable to use in internal error messages and provide some additional information about what kind of segment was involved in a problem
SegmentId	getId()	Returns the SegmentId of this segment, if it is backed by a real table, otherwise returns null.
void	validateOrElseThrow(PolicyEnforcer policyEnforcer)	Validates if the segment complies with the policy restrictions on tables.

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

isTombstone

Constructor Details

HashJoinSegment

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

Parameters:

baseSegment - The left-hand side base segment

baseFilter - Filter for 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

referenceCloseable - Closeables for the right-hand side clauses

Method Details

getId

public SegmentId getId()

Description copied from interface: Segment

Returns the SegmentId of this segment, if it is backed by a real table, otherwise returns null.

Specified by:

getId in interface Segment

getDataInterval

public org.joda.time.Interval getDataInterval()

Specified by:

getDataInterval in interface Segment

as

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

Description copied from interface: Segment

Request an implementation of a particular interface.

All implementations of this method should be able to provide a CursorFactory. 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 CursorFactory and some new interface. That extension can also offer a Query that uses that new interface.

Implementations which accept classes other than known built-in interfaces such as CursorFactory 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, one of the following:

• CursorFactory, to make cursors to run queries. Never null.
• QueryableIndex, index object, if this is a memory-mapped regular segment.
• IndexedTable, table object, if this is a joinable indexed table.
• TimeBoundaryInspector, inspector for min/max timestamps, if supported by this segment.
• PhysicalSegmentInspector, inspector for physical segment details, if supported by this segment.
• MaxIngestedEventTimeInspector, inspector for DataSourceMetadataResultValue.getMaxIngestedEventTime()
• TopNOptimizationInspector, inspector containing information for topN specific optimizations
• CloseableShapeshifter, stepping stone to RowsAndColumns.
• BypassRestrictedSegment, a policy-aware segment, converted from a policy-enforced segment.

validateOrElseThrow

public void validateOrElseThrow(PolicyEnforcer policyEnforcer)

Description copied from interface: Segment

Validates if the segment complies with the policy restrictions on tables.

This should be called right before the segment is about to be processed by the query stack, and after ExecutionVertex.createSegmentMapFunction(PolicyEnforcer).

Specified by:

validateOrElseThrow in interface Segment

getDebugString

public String getDebugString()

Description copied from interface: Segment

Developer friendly string suitable to use in internal error messages and provide some additional information about what kind of segment was involved in a problem

Specified by:

getDebugString in interface Segment

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException