io.cdap.cdap.api.dataset.lib

Interface ObjectStore<T>

Type Parameters:

T - the type of objects in the store

All Superinterfaces:

AutoCloseable, BatchReadable<byte[],T>, BatchWritable<byte[],T>, Closeable, Dataset

@Beta
public interface ObjectStore<T>
extends Dataset, BatchReadable<byte[],T>, BatchWritable<byte[],T>

A dataset that stores objects of a particular class into a table.

Supported types are:

• a plain java class
• a parametrized class
• a static inner class of one of the above

Interfaces and not-static inner classes are not supported. An ObjectStore will serialize the entire object and store it in a single column. See ObjectMappedTable if you want object fields to be mapped to their own columns.

Field Summary

Fields

Modifier and Type	Field and Description
static String	TYPE Type name

Method Summary

Modifier and Type	Method and Description
void	delete(byte[] key) Delete the object for the specified key.
List<Split>	getSplits(int numSplits, byte[] start, byte[] stop) Returns splits for a range of keys in the table.
T	read(byte[] key) Read an object with a given key.
T	read(String key) Read an object with a given key.
CloseableIterator<KeyValue<byte[],T>>	scan(byte[] startRow, byte[] stopRow) Scans table.
void	write(byte[] key, T object) Write an object with a given key.
void	write(String key, T object) Write an object with a given key.

Methods inherited from interface java.io.Closeable

close

Methods inherited from interface io.cdap.cdap.api.data.batch.BatchReadable

createSplitReader, getSplits

Field Detail

TYPE

static final String TYPE

Type name

See Also:

Constant Field Values

Method Detail

write

void write(String key,
           T object)

Write an object with a given key.

Parameters:

key - the key of the object

object - the object to be stored

write

void write(byte[] key,
           T object)

Write an object with a given key.

Specified by:

write in interface BatchWritable<byte[],T>

Parameters:

key - the key of the object

object - the object to be stored

read

T read(String key)

Read an object with a given key.

Parameters:

key - the key of the object

Returns:

the object if found, or null if not found

read

T read(byte[] key)

Read an object with a given key.

Parameters:

key - the key of the object

Returns:

the object if found, or null if not found

scan

CloseableIterator<KeyValue<byte[],T>> scan(byte[] startRow,
                                           byte[] stopRow)

Scans table.

Parameters:

startRow - start row inclusive. null means start from first row of the table

stopRow - stop row exclusive. null means scan all rows to the end of the table

Returns:

CloseableIterator over KeyValue<byte[], T>

delete

void delete(byte[] key)

Delete the object for the specified key.

Parameters:

key - key of the object to be deleted

getSplits

List<Split> getSplits(int numSplits,
                      byte[] start,
                      byte[] stop)

Returns splits for a range of keys in the table.

Parameters:

numSplits - Desired number of splits. If greater than zero, at most this many splits will be returned. If less than or equal to zero, any number of splits can be returned.

start - if non-null, the returned splits will only cover keys that are greater or equal

stop - if non-null, the returned splits will only cover keys that are less

Returns:

list of Split