org.apache.drill.exec.vector.accessor.writer

Class RepeatedListWriter

java.lang.Object

org.apache.drill.exec.vector.accessor.writer.AbstractArrayWriter

org.apache.drill.exec.vector.accessor.writer.AbstractArrayWriter.BaseArrayWriter

org.apache.drill.exec.vector.accessor.writer.ObjectArrayWriter

org.apache.drill.exec.vector.accessor.writer.RepeatedListWriter

All Implemented Interfaces:

ArrayWriter, ColumnWriter, WriterEvents, WriterPosition

public class RepeatedListWriter
extends ObjectArrayWriter

Implements a writer for a repeated list. A repeated list is really an array of arrays. It is an "array" because it does not support nulls. (The Drill [non-repeated] "list vector" does support nulls.) The terminology is confusing, but it is what Drill has settled upon.

Because repeated lists can be nested, they support incremental construction. Build the outer array, then the inner, then the leaf to build a 3D array. Since building is incremental, this form of array must track state and use the state to keep the newly-added element writer in sync.

To keep things (relatively) simple, the repeated list array starts out with an inner list. For the row set writer, the inner list is the actual element writer. For the result set loader, the inner list is a dummy, to be replaced by the real one once it is discovered by reading data (or by parsing a schema.)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	RepeatedListWriter.ArrayListener

Nested classes/interfaces inherited from class org.apache.drill.exec.vector.accessor.writer.AbstractArrayWriter

AbstractArrayWriter.ArrayElementWriterIndex, AbstractArrayWriter.ArrayObjectWriter, AbstractArrayWriter.BaseArrayWriter

Nested classes/interfaces inherited from interface org.apache.drill.exec.vector.accessor.writer.WriterEvents

WriterEvents.ColumnWriterListener, WriterEvents.State

Field Summary

Fields inherited from class org.apache.drill.exec.vector.accessor.writer.AbstractArrayWriter

elementIndex, elementObjWriter, offsetsWriter, outerIndex

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	RepeatedListWriter(ColumnMetadata schema, UInt4Vector offsetVector, AbstractObjectWriter elementWriter)

Method Summary

Modifier and Type	Method and Description
void	bindListener(RepeatedListWriter.ArrayListener listener)
static AbstractObjectWriter	buildRepeatedList(ColumnMetadata schema, RepeatedListVector vector, AbstractObjectWriter elementWriter)
AbstractObjectWriter	defineElement(ColumnMetadata schema)
AbstractObjectWriter	defineElement(MaterializedField schema)
void	endWrite() End a batch: finalize any vector values.
void	saveRow() Saves a row.
void	startRow() Start a new row.
void	startWrite() Start a write (batch) operation.

Methods inherited from class org.apache.drill.exec.vector.accessor.writer.ObjectArrayWriter

save, setObject

Methods inherited from class org.apache.drill.exec.vector.accessor.writer.AbstractArrayWriter.BaseArrayWriter

bindIndex, dump, endArrayValue, lastWriteIndex, postRollover, preRollover, restartRow

Methods inherited from class org.apache.drill.exec.vector.accessor.writer.AbstractArrayWriter

array, bindListener, copy, dict, entry, entryType, isProjected, nullable, offsetWriter, rowStartIndex, scalar, schema, setNull, setNull, size, tuple, type, variant, writeIndex

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RepeatedListWriter

protected RepeatedListWriter(ColumnMetadata schema,
                             UInt4Vector offsetVector,
                             AbstractObjectWriter elementWriter)

Method Detail

buildRepeatedList

public static AbstractObjectWriter buildRepeatedList(ColumnMetadata schema,
                                                     RepeatedListVector vector,
                                                     AbstractObjectWriter elementWriter)

bindListener

public void bindListener(RepeatedListWriter.ArrayListener listener)

defineElement

public AbstractObjectWriter defineElement(MaterializedField schema)

defineElement

public AbstractObjectWriter defineElement(ColumnMetadata schema)

startWrite

public void startWrite()

Description copied from interface: WriterEvents

Start a write (batch) operation. Performs any vector initialization required at the start of a batch (especially for offset vectors.)

Specified by:

startWrite in interface WriterEvents

Overrides:

startWrite in class AbstractArrayWriter.BaseArrayWriter

startRow

public void startRow()

Description copied from interface: WriterEvents

Start a new row. To be called only when a row is not active. To restart a row, call WriterEvents.restartRow() instead.

Specified by:

startRow in interface WriterEvents

Overrides:

startRow in class AbstractArrayWriter.BaseArrayWriter

saveRow

public void saveRow()

Description copied from interface: WriterEvents

Saves a row. Commits offset vector locations and advances each to the next position. Can be called only when a row is active.

Specified by:

saveRow in interface WriterEvents

Overrides:

saveRow in class AbstractArrayWriter.BaseArrayWriter

endWrite

public void endWrite()

Description copied from interface: WriterEvents

End a batch: finalize any vector values.

Specified by:

endWrite in interface WriterEvents

Overrides:

endWrite in class AbstractArrayWriter.BaseArrayWriter