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

Class BaseVarWidthWriter

java.lang.Object

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

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

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

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

All Implemented Interfaces:

ColumnWriter, ScalarWriter, ValueWriter, WriterEvents, WriterPosition

Direct Known Subclasses:

ColumnAccessors.Var16CharColumnWriter, ColumnAccessors.VarBinaryColumnWriter, ColumnAccessors.VarCharColumnWriter, ColumnAccessors.VarDecimalColumnWriter

public abstract class BaseVarWidthWriter
extends BaseScalarWriter

Base class for variable-width (VarChar, VarBinary, etc.) writers. Handles the additional complexity that such writers work with both an offset vector and a data vector. The offset vector is written using a specialized offset vector writer. The last write index is defined as the the last write position in the offset vector; not the last write position in the variable-width vector.

Most and value events are forwarded to the offset vector.

This class handles filling empty values with a default value. Doing so is trick as we must coordinate both this vector and the offset vector; checking for resize and overflow on each step. Also, when filling empties, we cannot use the normal "set" functions as they are what trigger the empty filling. Instead, we have to write to the "last write" position, not the current row positon.

Nested Class Summary

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

AbstractScalarWriterImpl.ScalarObjectWriter

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

WriterEvents.ColumnWriterListener, WriterEvents.State

Field Summary

Fields

Modifier and Type	Field and Description
protected OffsetVectorWriterImpl	offsetsWriter

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

capacity, drillBuf, emptyValue, listener, MIN_BUFFER_SIZE

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

schema, vectorIndex

Constructor Summary

Constructors

Constructor and Description
BaseVarWidthWriter(UInt4Vector offsetVector)

Method Summary

Modifier and Type	Method and Description
void	bindIndex(ColumnWriterIndex index) Bind the writer to a writer index.
void	dump(HierarchicalFormatter format)
void	endWrite() End a batch: finalize any vector values.
int	lastWriteIndex() Return the last write position in the vector.
void	postRollover() The vectors backing this writer rolled over.
protected int	prepareAppend(int width)
protected int	prepareWrite(int width)
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.
protected void	setBuffer() All change of buffer comes through this function to allow capturing the buffer address and capacity.
void	skipNulls()
void	startRow() Start a new row.
void	startWrite() Start a write (batch) operation.

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

appendBytes, bindListener, bindSchema, canExpand, nullable, overflowed, realloc, setBoolean, setBytes, setDate, setDecimal, setDouble, setFloat, setInt, setLong, setNull, setPeriod, setString, setTime, setTimestamp

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

endArrayValue, isProjected, rowStartIndex, saveRow, schema, type, vector, writeIndex

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

conversionError, extendedType, setObject, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.drill.exec.vector.accessor.ScalarWriter

setDefaultValue, valueType

Methods inherited from interface org.apache.drill.exec.vector.accessor.ColumnWriter

copy

Methods inherited from interface org.apache.drill.exec.vector.accessor.ValueWriter

setValue

Field Detail

offsetsWriter

protected final OffsetVectorWriterImpl offsetsWriter

Constructor Detail

BaseVarWidthWriter

public BaseVarWidthWriter(UInt4Vector offsetVector)

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 AbstractScalarWriterImpl

Parameters:

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

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 AbstractScalarWriterImpl

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 AbstractScalarWriterImpl

prepareWrite

protected final int prepareWrite(int width)

prepareAppend

protected final int prepareAppend(int width)

setBuffer

protected final void setBuffer()

Description copied from class: BaseScalarWriter

All change of buffer comes through this function to allow capturing the buffer address and capacity. Only two ways to set the buffer: by binding to a vector in bindVector(), or by resizing the vector in prepareWrite().

Specified by:

setBuffer in class BaseScalarWriter

skipNulls

public void skipNulls()

Specified by:

skipNulls in class BaseScalarWriter

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.

lastWriteIndex

public int lastWriteIndex()

Description copied from interface: WriterPosition

Return the last write position in the vector. This may be the same as the writer index position (if the vector was written at that point), or an earlier point. In either case, this value points to the last valid value in the vector.

Returns:

index of the last valid value in the vector

preRollover

public final 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.

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.

endWrite

public final void endWrite()

Description copied from interface: WriterEvents

End a batch: finalize any vector values.

dump

public void dump(HierarchicalFormatter format)

Specified by:

dump in interface WriterEvents

Overrides:

dump in class BaseScalarWriter