Package org.apache.druid.segment

Interface Segment

All Superinterfaces:

AutoCloseable, Closeable

All Known Implementing Classes:

ArrayListSegment, FilteredSegment, FrameSegment, HashJoinSegment, IncrementalIndexSegment, LookupSegment, QueryableIndexSegment, ReferenceCountedSegmentProvider.CloseableWrappedReference, ReferenceCountedSegmentProvider.LeafReference, ReferenceCountedSegmentProvider.ReferenceClosingSegment, ReferenceCountedSegmentProvider.UnmanagedReference, RestrictedSegment, RowBasedSegment, UnnestSegment, WrappedSegment

public interface Segment
extends Closeable

The difference between this class and DataSegment is that DataSegment contains the segment metadata only, while this class represents the actual body of segment data, queryable.

Method Summary

Modifier and Type	Method	Description
<T> T	as(Class<T> clazz)	Request an implementation of a particular interface.
org.joda.time.Interval	getDataInterval()
default 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.
default boolean	isTombstone()
default void	validateOrElseThrow(PolicyEnforcer policyEnforcer)	Validates if the segment complies with the policy restrictions on tables.

Methods inherited from interface java.io.Closeable

close

Method Details

getId

@Nullable
SegmentId getId()

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

getDataInterval

org.joda.time.Interval getDataInterval()

as

@Nullable
<T> T as(@Nonnull
 Class<T> clazz)

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.

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.

isTombstone

default boolean isTombstone()

getDebugString

default 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

validateOrElseThrow

default void validateOrElseThrow(PolicyEnforcer policyEnforcer)

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).