Package org.apache.druid.segment

Class QueryableIndexColumnSelectorFactory

java.lang.Object

org.apache.druid.segment.QueryableIndexColumnSelectorFactory

All Implemented Interfaces:

Expr.InputBindingInspector, ColumnInspector, ColumnSelectorFactory, RowIdSupplier

public class QueryableIndexColumnSelectorFactory
extends Object
implements ColumnSelectorFactory, RowIdSupplier

The basic implementation of ColumnSelectorFactory over a historical segment (i. e. QueryableIndex). It's counterpart for incremental index is IncrementalIndexColumnSelectorFactory.

Field Summary

Fields

Modifier and Type	Field	Description
protected ReadableOffset	offset

Fields inherited from interface org.apache.druid.segment.RowIdSupplier

INIT

Constructor Summary

Constructors

Constructor	Description
QueryableIndexColumnSelectorFactory(VirtualColumns virtualColumns, boolean descending, ReadableOffset offset, ColumnCache columnCache)

Method Summary

Modifier and Type	Method	Description
ColumnCapabilities	getColumnCapabilities(String columnName)	Returns capabilities of a particular column, if known.
long	getRowId()	Returns a number that uniquely identifies the current position of some underlying cursor.
RowIdSupplier	getRowIdSupplier()	Returns a RowIdSupplier that allows callers to detect whether the selectors returned by this factory have moved or not.
ColumnValueSelector<?>	makeColumnValueSelector(String columnName)	Returns ColumnValueSelector corresponding to the given column name, or NilColumnValueSelector if the column with such name is absent.
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

getColumnCapabilitiesWithDefault, getType

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

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

Field Detail

offset

protected final ReadableOffset offset

Constructor Detail

QueryableIndexColumnSelectorFactory

public QueryableIndexColumnSelectorFactory(VirtualColumns virtualColumns,
                                           boolean descending,
                                           ReadableOffset offset,
                                           ColumnCache columnCache)

Method Detail

makeDimensionSelector

public DimensionSelector makeDimensionSelector(DimensionSpec dimensionSpec)

Specified by:

makeDimensionSelector in interface ColumnSelectorFactory

makeColumnValueSelector

public ColumnValueSelector<?> makeColumnValueSelector(String columnName)

Description copied from interface: ColumnSelectorFactory

Returns ColumnValueSelector corresponding to the given column name, or NilColumnValueSelector if the column with such name is absent.

Specified by:

makeColumnValueSelector in interface ColumnSelectorFactory

getRowIdSupplier

@Nullable
public RowIdSupplier getRowIdSupplier()

Description copied from interface: ColumnSelectorFactory

Returns a RowIdSupplier that allows callers to detect whether the selectors returned by this factory have moved or not. Useful for selectors that wrap other selectors, such as virtual columns, as it allows them to cache their outputs.

Specified by:

getRowIdSupplier in interface ColumnSelectorFactory

getRowId

public long getRowId()

Description copied from interface: RowIdSupplier

Returns a number that uniquely identifies the current position of some underlying cursor. This is useful for caching: it is safe to assume nothing has changed in the selector as long as the row ID stays the same. Row IDs do not need to be contiguous or monotonic. They need not have any meaning. In particular: they may not be row *numbers* (row number 0 may have any arbitrary row ID). Valid row IDs are always nonnegative.

Specified by:

getRowId in interface RowIdSupplier

getColumnCapabilities

@Nullable
public ColumnCapabilities getColumnCapabilities(String columnName)

Description copied from interface: ColumnSelectorFactory

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.

Specified by:

getColumnCapabilities in interface ColumnInspector

Specified by:

getColumnCapabilities in interface ColumnSelectorFactory

Parameters:

columnName - column name

Returns:

capabilities, or null