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, IntervalDayTimeColumnVector, LongColumnVector, MultiValuedColumnVector, StructColumnVector, TimestampColumnVector, UnionColumnVector

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.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ColumnVector.Type

Field Summary

Fields

Modifier and Type	Field and Description
boolean[]	isNull
boolean	isRepeating
boolean	noNulls

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
void	ensureSize(int size, boolean presesrveData) Ensure the ColumnVector can hold at least size values.
abstract void	flatten(boolean selectedInUse, int[] sel, int size)
protected void	flattenNoNulls(boolean selectedInUse, int[] sel, int size)
protected void	flattenPush()
protected void	flattenRepeatingNulls(boolean selectedInUse, int[] sel, int size)
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	setRepeating(boolean isRepeating) Sets the isRepeating flag.
abstract void	stringifyValue(StringBuilder buffer, int row) Print the value for this column into the given string builder.
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

reset

public void reset()

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

setRepeating

public void setRepeating(boolean isRepeating)

Sets the isRepeating flag. Recurses over structs and unions so that the flags are set correctly.

Parameters:

isRepeating -

flatten

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

flattenRepeatingNulls

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

flattenNoNulls

protected 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. This method can assume that the output does not have isRepeating set.

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.

ensureSize

public void ensureSize(int size,
                       boolean presesrveData)

Ensure the ColumnVector can hold at least size values. This method is deliberately *not* recursive because the complex types can easily have more (or less) children than the upper levels.

Parameters:

size - the new minimum size

presesrveData - should the old data be preserved?

stringifyValue

public abstract void stringifyValue(StringBuilder buffer,
                                    int row)

Print the value for this column into the given string builder.

Parameters:

buffer - the buffer to print into

row - the id of the row to print