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

Class ListWriterImpl

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.ListWriterImpl

All Implemented Interfaces:

ArrayWriter, ColumnWriter, WriterEvents, WriterPosition

public class ListWriterImpl
extends ObjectArrayWriter

List writer, which is basically an array writer, with the addition that each list element can be null. Lists never auto-increment their indexes since the contents of lists can change dynamically, and auto-increment is meaningful only for scalar arrays.

Nested Class Summary

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

Constructor and Description
ListWriterImpl(ColumnMetadata schema, ListVector vector, AbstractObjectWriter memberWriter)

Method Summary

Modifier and Type	Method and Description
void	bindIndex(ColumnWriterIndex index) Bind the writer to a writer index.
void	endArrayValue() End a value.
void	endWrite() End a batch: finalize any vector values.
void	postRollover() The vectors backing this writer rolled over.
void	preRollover() The vectors backing this vector are about to roll over.
void	restartRow() During a writer to a row, rewind the the current index position to restart the row.
void	saveRow() Saves a row.
void	setNull(boolean isNull)
void	setObject(Object array) Generic technique to write data as a generic Java object.
void	startRow() Start a new row.
void	startWrite() Start a write (batch) operation.
ListVector	vector()

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

save

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

dump, lastWriteIndex

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, 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

ListWriterImpl

public ListWriterImpl(ColumnMetadata schema,
                      ListVector vector,
                      AbstractObjectWriter memberWriter)

Method Detail

bindIndex

public void bindIndex(ColumnWriterIndex index)

Description copied from interface: WriterEvents

Bind the writer to a writer index.

Specified by:

bindIndex in interface WriterEvents

Overrides:

bindIndex in class AbstractArrayWriter.BaseArrayWriter

Parameters:

index - the writer index (top level or nested for arrays)

vector

public ListVector vector()

setNull

public void setNull(boolean isNull)

Specified by:

setNull in interface ArrayWriter

Overrides:

setNull in class AbstractArrayWriter

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

endArrayValue

public void endArrayValue()

Description copied from interface: WriterEvents

End a value. Similar to WriterEvents.saveRow(), but the save of a value is conditional on saving the row. This version is primarily of use in tuples nested inside arrays: it saves each tuple within the array, advancing to a new position in the array. The update of the array's offset vector based on the cumulative value saves is done when saving the row.

Specified by:

endArrayValue in interface WriterEvents

Overrides:

endArrayValue in class AbstractArrayWriter.BaseArrayWriter

restartRow

public void restartRow()

Description copied from interface: WriterEvents

During a writer to a row, rewind the the current index position to restart the row. Done when abandoning the current row, such as when filtering out a row at read time.

Specified by:

restartRow in interface WriterEvents

Overrides:

restartRow 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

preRollover

public void preRollover()

Description copied from interface: WriterEvents

The vectors backing this vector are about to roll over. Finish the current batch up to, but not including, the current row.

Specified by:

preRollover in interface WriterEvents

Overrides:

preRollover in class AbstractArrayWriter.BaseArrayWriter

postRollover

public void postRollover()

Description copied from interface: WriterEvents

The vectors backing this writer rolled over. This means that data for the current row has been rolled over into a new vector. Offsets and indexes should be shifted based on the understanding that data for the current row now resides at the start of a new vector instead of its previous location elsewhere in an old vector.

Specified by:

postRollover in interface WriterEvents

Overrides:

postRollover 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

setObject

public void setObject(Object array)

Description copied from interface: ColumnWriter

Generic technique to write data as a generic Java object. The type of the object must match the target writer. Primarily for testing.

• Scalar: The type of the Java object must match the type of the target vector. String or byte[] can be used for Varchar vectors.
• Array: Write the array given an array of values. The object must be a Java array. The type of the array must match the type of element in the repeated vector. That is, if the vector is a Repeated Int, provide an int[] array.
• Tuple (map or row): The Java object must be an array of objects in which the members of the array have a 1:1 correspondence with the members of the tuple in the order defined by the writer metadata. That is, if the map is (Int, Varchar), provide a Object[] array like this: {10, "fred"}.
• Union: Uses the Java object type to determine the type of the backing vector. Creates a vector of the required type if needed.

Specified by:

setObject in interface ColumnWriter

Overrides:

setObject in class ObjectArrayWriter

Parameters:

array - value to write to the vector. The Java type of the object indicates the Drill storage type