Package org.apache.druid.frame.field

Interface FieldReader

All Known Implementing Classes:

ComplexFieldReader, DoubleArrayFieldReader, DoubleFieldReader, FloatArrayFieldReader, FloatFieldReader, LongArrayFieldReader, LongFieldReader, NumericArrayFieldReader, NumericFieldReader, StringArrayFieldReader, StringFieldReader

public interface FieldReader

Embeds the logic to read a specific field from row-based frames or from RowKey.

Most callers should use FrameReader or RowKeyReader rather than using this interface directly.

Stateless and immutable.

Method Summary

Modifier and Type	Method	Description
boolean	isNull(org.apache.datasketches.memory.Memory memory, long position)	Whether the provided memory position points to a null value.
ColumnValueSelector<?>	makeColumnValueSelector(org.apache.datasketches.memory.Memory memory, ReadableFieldPointer fieldPointer)	Create a ColumnValueSelector backed by some memory and a moveable pointer.
DimensionSelector	makeDimensionSelector(org.apache.datasketches.memory.Memory memory, ReadableFieldPointer fieldPointer, ExtractionFn extractionFn)	Create a DimensionSelector backed by some memory and a moveable pointer.
Column	makeRACColumn(Frame frame, RowSignature signature, String columnName)	Create a Column which provides accses to the rows in the frame, via the Column.toAccessor().

Method Details

makeRACColumn

Column makeRACColumn(Frame frame,
 RowSignature signature,
 String columnName)

Create a Column which provides accses to the rows in the frame, via the Column.toAccessor().

makeColumnValueSelector

ColumnValueSelector<?> makeColumnValueSelector(org.apache.datasketches.memory.Memory memory,
 ReadableFieldPointer fieldPointer)

Create a ColumnValueSelector backed by some memory and a moveable pointer.

makeDimensionSelector

DimensionSelector makeDimensionSelector(org.apache.datasketches.memory.Memory memory,
 ReadableFieldPointer fieldPointer,
 @Nullable
 ExtractionFn extractionFn)

Create a DimensionSelector backed by some memory and a moveable pointer.

isNull

boolean isNull(org.apache.datasketches.memory.Memory memory,
 long position)

Whether the provided memory position points to a null value.