org.apache.druid.segment

Interface ColumnSelectorFactory

All Superinterfaces:

ColumnInspector, Expr.InputBindingInspector

All Known Implementing Classes:

AllNullColumnSelectorFactory, DefaultColumnSelectorFactoryMaker.ColumnAccessorBasedColumnSelectorFactory, FrameColumnSelectorFactory, IndexedTableColumnSelectorFactory, LookupColumnSelectorFactory, MultiColumnSelectorFactory, QueryableIndexColumnSelectorFactory, RowBasedColumnSelectorFactory, VirtualizedColumnSelectorFactory

public interface ColumnSelectorFactory
extends ColumnInspector

Factory class for MetricSelectors

See Also:

org.apache.druid.segment.vector.VectorColumnSelectorFactory, the vectorized version

Method Summary

Modifier and Type	Method and Description
ColumnCapabilities	getColumnCapabilities(String column) Returns capabilities of a particular column, if known.
default 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 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

Method Detail

makeDimensionSelector

DimensionSelector makeDimensionSelector(DimensionSpec dimensionSpec)

makeColumnValueSelector

ColumnValueSelector makeColumnValueSelector(String columnName)

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

getColumnCapabilities

@Nullable
ColumnCapabilities getColumnCapabilities(String column)

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

Parameters:

column - column name

Returns:

capabilities, or null

getRowIdSupplier

@Nullable
default RowIdSupplier getRowIdSupplier()

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.