org.apache.pig.backend.datastorage

Interface DataStorage

All Known Implementing Classes:

HDataStorage

public interface DataStorage

DataStorage provides an abstraction of a generic container. Special instances of it can be a file system.

Field Summary

Fields

Modifier and Type	Field and Description
static String	RAW_CAPACITY_KEY
static String	RAW_USED_KEY
static String	USED_BYTES_KEY

Method Summary

Modifier and Type	Method and Description
ElementDescriptor[]	asCollection(String pattern)
ContainerDescriptor	asContainer(ContainerDescriptor container)
ContainerDescriptor	asContainer(ContainerDescriptor parent, ContainerDescriptor child)
ContainerDescriptor	asContainer(ContainerDescriptor parent, String child)
ContainerDescriptor	asContainer(String name) Created an entity handle for a container.
ContainerDescriptor	asContainer(String parent, String child)
ElementDescriptor	asElement(ContainerDescriptor parent, ElementDescriptor child)
ElementDescriptor	asElement(ContainerDescriptor parent, String child)
ElementDescriptor	asElement(ElementDescriptor element)
ElementDescriptor	asElement(String name) Creates an entity handle for an object (no containment relation) from a String
ElementDescriptor	asElement(String parent, String child)
void	close() Clean-up and releasing of resources.
ContainerDescriptor	getActiveContainer()
Properties	getConfiguration() Provides configuration information about the storage itself.
Map<String,Object>	getStatistics() Provides statistics on the Storage: capacity values, how much storage is in use...
void	init() Place holder for possible initialization activities.
boolean	isContainer(String name)
void	setActiveContainer(ContainerDescriptor container)
void	updateConfiguration(Properties newConfiguration) Provides a way to change configuration parameters at the Data Storage level.

Field Detail

USED_BYTES_KEY

static final String USED_BYTES_KEY

See Also:

Constant Field Values

RAW_CAPACITY_KEY

static final String RAW_CAPACITY_KEY

See Also:

Constant Field Values

RAW_USED_KEY

static final String RAW_USED_KEY

See Also:

Constant Field Values

Method Detail

init

void init()

Place holder for possible initialization activities.

close

void close()
    throws IOException

Clean-up and releasing of resources.

Throws:

IOException

getConfiguration

Properties getConfiguration()

Provides configuration information about the storage itself. For instance global data-replication policies if any, default values, ... Some of such values could be overridden at a finer granularity (e.g. on a specific object in the Data Storage)

Returns:

- configuration information

updateConfiguration

void updateConfiguration(Properties newConfiguration)
                  throws DataStorageException

Provides a way to change configuration parameters at the Data Storage level. For instance, change the data replication policy.

Parameters:

newConfiguration - - the new configuration settings

Throws:

when - configuration conflicts are detected

DataStorageException

getStatistics

Map<String,Object> getStatistics()
                          throws IOException

Provides statistics on the Storage: capacity values, how much storage is in use...

Returns:

statistics on the Data Storage

Throws:

IOException

asElement

ElementDescriptor asElement(String name)
                     throws DataStorageException

Creates an entity handle for an object (no containment relation) from a String

Parameters:

name - of the object

Returns:

an object descriptor

Throws:

DataStorageException - if name does not conform to naming convention enforced by the Data Storage.

asElement

ElementDescriptor asElement(ElementDescriptor element)
                     throws DataStorageException

Throws:

DataStorageException

asElement

ElementDescriptor asElement(String parent,
                            String child)
                     throws DataStorageException

Throws:

DataStorageException

asElement

ElementDescriptor asElement(ContainerDescriptor parent,
                            String child)
                     throws DataStorageException

Throws:

DataStorageException

asElement

ElementDescriptor asElement(ContainerDescriptor parent,
                            ElementDescriptor child)
                     throws DataStorageException

Throws:

DataStorageException

isContainer

boolean isContainer(String name)
             throws DataStorageException

Throws:

DataStorageException

asContainer

ContainerDescriptor asContainer(String name)
                         throws DataStorageException

Created an entity handle for a container.

Parameters:

name - of the container

Returns:

a container descriptor

Throws:

DataStorageException - if name does not conform to naming convention enforced by the Data Storage.

asContainer

ContainerDescriptor asContainer(ContainerDescriptor container)
                         throws DataStorageException

Throws:

DataStorageException

asContainer

ContainerDescriptor asContainer(String parent,
                                String child)
                         throws DataStorageException

Throws:

DataStorageException

asContainer

ContainerDescriptor asContainer(ContainerDescriptor parent,
                                String child)
                         throws DataStorageException

Throws:

DataStorageException

asContainer

ContainerDescriptor asContainer(ContainerDescriptor parent,
                                ContainerDescriptor child)
                         throws DataStorageException

Throws:

DataStorageException

asCollection

ElementDescriptor[] asCollection(String pattern)
                          throws DataStorageException

Throws:

DataStorageException

setActiveContainer

void setActiveContainer(ContainerDescriptor container)

getActiveContainer

ContainerDescriptor getActiveContainer()