org.apache.hadoop.hive.ql.exec.vector
Class ColumnVector

java.lang.Object
  org.apache.hadoop.hive.ql.exec.vector.ColumnVector

Direct Known Subclasses:

BytesColumnVector, DecimalColumnVector, DoubleColumnVector, LongColumnVector

public abstract class ColumnVector
extends Object

ColumnVector contains the shared structure for the sub-types, including NULL information, and whether this vector repeats, i.e. has all values the same, so only the first one is set. This is used to accelerate query performance by handling a whole vector in O(1) time when applicable. The fields are public by design since this is a performance-critical structure that is used in the inner loop of query execution.

Field Summary

boolean[]	isNull
boolean	isRepeating
boolean	noNulls

Constructor Summary

ColumnVector(int len)
Constructor for super-class ColumnVector.

Method Summary

abstract void	flatten(boolean selectedInUse, int[] sel, int size)
void	flattenNoNulls(boolean selectedInUse, int[] sel, int size)
protected void	flattenPush()
void	flattenRepeatingNulls(boolean selectedInUse, int[] sel, int size)
abstract org.apache.hadoop.io.Writable	getWritableObject(int index)
void	init() Initialize the column vector.
void	reset() Resets the column to default state - fills the isNull array with false - sets noNulls to true - sets isRepeating to false
abstract void	setElement(int outElementNum, int inputElementNum, ColumnVector inputVector) Set the element in this column vector from the given input vector.
void	unFlatten() Restore the state of isRepeating and noNulls to what it was before flattening.

Methods inherited from class java.lang.Object

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

Field Detail

isNull

public boolean[] isNull

noNulls

public boolean noNulls

isRepeating

public boolean isRepeating

Constructor Detail

ColumnVector

public ColumnVector(int len)

Constructor for super-class ColumnVector. This is not called directly, but used to initialize inherited fields.

Parameters:

len - Vector length

Method Detail

getWritableObject

public abstract org.apache.hadoop.io.Writable getWritableObject(int index)

reset

public void reset()

Resets the column to default state - fills the isNull array with false - sets noNulls to true - sets isRepeating to false

flatten

public abstract void flatten(boolean selectedInUse,
                             int[] sel,
                             int size)

flattenRepeatingNulls

public void flattenRepeatingNulls(boolean selectedInUse,
                                  int[] sel,
                                  int size)

flattenNoNulls

public void flattenNoNulls(boolean selectedInUse,
                           int[] sel,
                           int size)

unFlatten

public void unFlatten()

Restore the state of isRepeating and noNulls to what it was before flattening. This must only be called just after flattening and then evaluating a VectorExpression on the column vector. It is an optimization that allows other operations on the same column to continue to benefit from the isRepeating and noNulls indicators.

flattenPush

protected void flattenPush()

setElement

public abstract void setElement(int outElementNum,
                                int inputElementNum,
                                ColumnVector inputVector)

Set the element in this column vector from the given input vector.

init

public void init()

Initialize the column vector. This method can be overridden by specific column vector types. Use this method only if the individual type of the column vector is not known, otherwise its preferable to call specific initialization methods.