Package org.apache.druid.frame.segment.columnar

Class ColumnarFrameCursorFactory

java.lang.Object

org.apache.druid.frame.segment.columnar.ColumnarFrameCursorFactory

All Implemented Interfaces:

Expr.InputBindingInspector, ColumnInspector, CursorFactory

public class ColumnarFrameCursorFactory
extends Object
implements CursorFactory

A CursorFactory implementation based on a single columnar Frame. This class is only used for columnar frames. It is not used for row-based frames.

See Also:

• the row-based version

Constructor Summary

Constructors

Constructor	Description
ColumnarFrameCursorFactory(Frame frame, RowSignature signature, List<FrameColumnReader> columnReaders)

Method Summary

Modifier and Type	Method	Description
ColumnCapabilities	getColumnCapabilities(String column)	Returns capabilities of a particular column, if known.
RowSignature	getRowSignature()	Returns the RowSignature of the data available from this cursor factory.
CursorHolder	makeCursorHolder(CursorBuildSpec spec)	Creates a CursorHolder for a given CursorBuildSpec which describes how the reader is going to scan, filter, transform, group and aggregate, and/or order the data.

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.ColumnInspector

getType

Methods inherited from interface org.apache.druid.math.expr.Expr.InputBindingInspector

areNumeric, areNumeric, areSameTypes, areSameTypes, areScalar, areScalar, canVectorize, canVectorize

Constructor Details

ColumnarFrameCursorFactory

public ColumnarFrameCursorFactory(Frame frame,
 RowSignature signature,
 List<FrameColumnReader> columnReaders)

Method Details

makeCursorHolder

public CursorHolder makeCursorHolder(CursorBuildSpec spec)

Description copied from interface: CursorFactory

Creates a CursorHolder for a given CursorBuildSpec which describes how the reader is going to scan, filter, transform, group and aggregate, and/or order the data.

Specified by:

makeCursorHolder in interface CursorFactory

getRowSignature

public RowSignature getRowSignature()

Description copied from interface: CursorFactory

Returns the RowSignature of the data available from this cursor factory. For mutable segments, even though the signature may evolve over time, any particular object returned by this method is an immutable snapshot.

Specified by:

getRowSignature in interface CursorFactory

getColumnCapabilities

@Nullable
public ColumnCapabilities getColumnCapabilities(String column)

Description copied from interface: CursorFactory

Returns capabilities of a particular column, if known. May be null if the column doesn't exist, or if the column does exist but the capabilities are unknown. The latter is possible with dynamically discovered columns. Note that CursorFactory are representations of "real" segments, so they are not aware of any virtual columns that may be involved in a query. In general, query engines should instead use the method ColumnSelectorFactory.getColumnCapabilities(String), which returns capabilities for virtual columns as well.

Specified by:

getColumnCapabilities in interface ColumnInspector

Specified by:

getColumnCapabilities in interface CursorFactory

Parameters:

column - column name

Returns:

capabilities, or null