Package org.apache.druid.query.scan

Class SettableCursorColumnSelectorFactory

java.lang.Object

org.apache.druid.query.scan.SettableCursorColumnSelectorFactory

All Implemented Interfaces:

Expr.InputBindingInspector, ColumnInspector, ColumnSelectorFactory

@NotThreadSafe
public class SettableCursorColumnSelectorFactory
extends Object
implements ColumnSelectorFactory

A column selector factory, that represents the column values from multiple underlying cursors. It essentially wraps over the multiple cursors and can be passed to methods that expect column value selector from a single cursor. It is the duty of the caller to know when to switch from one cursor to another It is expected to work correctly if the individual cursors have the same corresponding columns, columnTypes, and column capabilities since the usual pattern throughout the code is to cache these values and assume they are fixed throughout.

Constructor Summary

Constructors

Constructor	Description
SettableCursorColumnSelectorFactory(Supplier<Cursor> cursorSupplier, RowSignature rowSignature)

Method Summary

Modifier and Type	Method	Description
ColumnCapabilities	getColumnCapabilities(String column)	Return column capabilities from the signature.
RowIdSupplier	getRowIdSupplier()	Since we don't know all the cursors beforehand, we can't reconcile their row id suppliers to provide one here
ColumnValueSelector	makeColumnValueSelector(String columnName)	Create ColumnValueSelector for the give column name
DimensionSelector	makeDimensionSelector(DimensionSpec dimensionSpec)

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 Detail

SettableCursorColumnSelectorFactory

public SettableCursorColumnSelectorFactory(Supplier<Cursor> cursorSupplier,
                                           RowSignature rowSignature)

Method Detail

makeDimensionSelector

public DimensionSelector makeDimensionSelector(DimensionSpec dimensionSpec)

Specified by:

makeDimensionSelector in interface ColumnSelectorFactory

makeColumnValueSelector

public ColumnValueSelector makeColumnValueSelector(String columnName)

Create ColumnValueSelector for the give column name

Specified by:

makeColumnValueSelector in interface ColumnSelectorFactory

getColumnCapabilities

@Nullable
public ColumnCapabilities getColumnCapabilities(String column)

Return column capabilities from the signature. This returns the capabilities with the minimal assumptions. For example, one cursor can have capabilities with multivalues set to FALSE, while other can have it set to TRUE Creating the capabilites from the signature would leave the state undefined. If the caller has more knowledge about all the cursors that will get created, the caller can subclass and override the function with that information

Specified by:

getColumnCapabilities in interface ColumnInspector

Specified by:

getColumnCapabilities in interface ColumnSelectorFactory

Parameters:

column - column name

Returns:

capabilities, or null

getRowIdSupplier

@Nullable
public RowIdSupplier getRowIdSupplier()

Since we don't know all the cursors beforehand, we can't reconcile their row id suppliers to provide one here

Specified by:

getRowIdSupplier in interface ColumnSelectorFactory