Package org.h2.mvstore.db

Class NullValueDataType

java.lang.Object

org.h2.mvstore.db.NullValueDataType

All Implemented Interfaces:

Comparator<Value>, DataType<Value>

public final class NullValueDataType
extends Object
implements DataType<Value>

Dummy data type used when no value is required. This data type doesn't use any disk space and always returns SQL NULL value.

Field Summary

Fields

Modifier and Type	Field	Description
static final NullValueDataType	INSTANCE	Dummy data type instance.

Method Summary

Modifier and Type	Method	Description
int	binarySearch(Value key, Object storage, int size, int initialGuess)	Perform binary search for the key within the storage
int	compare(Value a, Value b)	Compare two keys.
Value[]	createStorage(int size)	Create storage object of array type to hold values
int	getMemory(Value obj)	Calculates the amount of used memory in bytes.
boolean	isMemoryEstimationAllowed()	Whether memory estimation based on previously seen values is allowed/desirable
Value	read(ByteBuffer buff)	Read an object.
void	read(ByteBuffer buff, Object storage, int len)	Read a list of objects.
void	write(WriteBuffer buff, Object storage, int len)	Write a list of objects.
void	write(WriteBuffer buff, Value obj)	Write an object.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals, reversed, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Field Details

INSTANCE

public static final NullValueDataType INSTANCE

Dummy data type instance.

Method Details

compare

public int compare(Value a,
 Value b)

Description copied from interface: DataType

Compare two keys.

Specified by:

compare in interface Comparator<Value>

Specified by:

compare in interface DataType<Value>

Parameters:

a - the first key

b - the second key

Returns:

-1 if the first key is smaller, 1 if larger, and 0 if equal

binarySearch

public int binarySearch(Value key,
 Object storage,
 int size,
 int initialGuess)

Description copied from interface: DataType

Perform binary search for the key within the storage

Specified by:

binarySearch in interface DataType<Value>

Parameters:

key - to search for

storage - to search within (an array of type T)

size - number of data items in the storage

initialGuess - for key position

Returns:

index of the key , if found, - index of the insertion point, if not

getMemory

public int getMemory(Value obj)

Description copied from interface: DataType

Calculates the amount of used memory in bytes.

Specified by:

getMemory in interface DataType<Value>

Parameters:

obj - the object

Returns:

the used memory

isMemoryEstimationAllowed

public boolean isMemoryEstimationAllowed()

Description copied from interface: DataType

Whether memory estimation based on previously seen values is allowed/desirable

Specified by:

isMemoryEstimationAllowed in interface DataType<Value>

Returns:

true if memory estimation is allowed

write

public void write(WriteBuffer buff,
 Value obj)

Description copied from interface: DataType

Write an object.

Specified by:

write in interface DataType<Value>

Parameters:

buff - the target buffer

obj - the value

write

public void write(WriteBuffer buff,
 Object storage,
 int len)

Description copied from interface: DataType

Write a list of objects.

Specified by:

write in interface DataType<Value>

Parameters:

buff - the target buffer

storage - the objects

len - the number of objects to write

read

public Value read(ByteBuffer buff)

Description copied from interface: DataType

Read an object.

Specified by:

read in interface DataType<Value>

Parameters:

buff - the source buffer

Returns:

the object

read

public void read(ByteBuffer buff,
 Object storage,
 int len)

Description copied from interface: DataType

Read a list of objects.

Specified by:

read in interface DataType<Value>

Parameters:

buff - the target buffer

storage - the objects

len - the number of objects to read

createStorage

public Value[] createStorage(int size)

Description copied from interface: DataType

Create storage object of array type to hold values

Specified by:

createStorage in interface DataType<Value>

Parameters:

size - number of values to hold

Returns:

storage object