org.apache.druid.segment

Class RowBasedColumnSelectorFactory<T>

java.lang.Object

org.apache.druid.segment.RowBasedColumnSelectorFactory<T>

All Implemented Interfaces:

Expr.InputBindingInspector, ColumnInspector, ColumnSelectorFactory

public class RowBasedColumnSelectorFactory<T>
extends Object
implements ColumnSelectorFactory

A ColumnSelectorFactory that is based on an object supplier and a RowAdapter for that type of object.

Method Summary

Modifier and Type	Method and Description
static <RowType> RowBasedColumnSelectorFactory<RowType>	create(RowAdapter<RowType> adapter, Supplier<RowType> supplier, ColumnInspector columnInspector, boolean throwParseExceptions, boolean useStringValueOfNullInLists) Create an instance based on any object, along with a RowAdapter for that object.
ColumnCapabilities	getColumnCapabilities(String columnName) Returns capabilities of a particular column, if known.
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

Method Detail

create

public static <RowType> RowBasedColumnSelectorFactory<RowType> create(RowAdapter<RowType> adapter,
                                                                      Supplier<RowType> supplier,
                                                                      ColumnInspector columnInspector,
                                                                      boolean throwParseExceptions,
                                                                      boolean useStringValueOfNullInLists)

Create an instance based on any object, along with a RowAdapter for that object.

Parameters:

adapter - adapter for these row objects

supplier - supplier of row objects

columnInspector - will be used for reporting available columns and their capabilities. Note that this factory will still allow creation of selectors on any named field in the rows, even if it doesn't appear in "columnInspector". (It only needs to be accessible via RowAdapter.columnFunction(java.lang.String).) As a result, you can achieve an untyped mode by passing in RowSignature.empty().

throwParseExceptions - whether numeric selectors should throw parse exceptions or use a default/null value when their inputs are not actually numeric

useStringValueOfNullInLists - whether nulls in multi-value strings should be replaced with the string "null". for example: the list ["a", null] would be converted to ["a", "null"]. Useful for callers that need compatibility with Rows.objectToStrings(java.lang.Object).

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

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