DataStore (Apache Gora 0.2 API)

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org.apache.gora.store
Interface DataStore<K,T extends Persistent>


Type Parameters:: K - the class of keys in the datastore; T - the class of persistent objects in the datastore

All Superinterfaces:: Closeable, org.apache.hadoop.conf.Configurable, org.apache.hadoop.io.Writable

All Known Subinterfaces:: FileBackedDataStore<K,T>

All Known Implementing Classes:: AccumuloStore, AvroStore, CassandraStore, DataFileAvroStore, DataStoreBase, FileBackedDataStoreBase, HBaseStore, MemStore, SqlStore

public interface DataStore<K,T extends Persistent>
extends Closeable, org.apache.hadoop.io.Writable, org.apache.hadoop.conf.Configurable
extends Closeable, org.apache.hadoop.io.Writable, org.apache.hadoop.conf.Configurable

DataStore handles actual object persistence. Objects can be persisted, fetched, queried or deleted by the DataStore methods. DataStores can be constructed by an instance of DataStoreFactory.

DataStores implementations should be thread safe.

Note: Results of updates (put(Object, Persistent), delete(Object) and deleteByQuery(Query) operations) are guaranteed to be visible to subsequent get / execute operations ONLY after a subsequent call to flush().

Method Summary

void close()
          Close the DataStore.

void createSchema()
          Creates the optional schema or table (or similar) in the datastore to hold the objects.

boolean delete(K key)
          Deletes the object with the given key

long deleteByQuery(Query<K,T> query)
          Deletes all the objects matching the query.

void deleteSchema()
          Deletes the underlying schema or table (or similar) in the datastore that holds the objects.

Result<K,T> execute(Query<K,T> query)
          Executes the given query and returns the results.

void flush()
          Forces the write caches to be flushed.

T get(K key)
          Returns the object corresponding to the given key fetching all the fields.

T get(K key, String[] fields)
          Returns the object corresponding to the given key.

BeanFactory<K,T> getBeanFactory()
          Returns the BeanFactory used by the DataStore

org.apache.hadoop.conf.Configuration getConf()


Class<K> getKeyClass()
          Returns the class of the keys

List<PartitionQuery<K,T>> getPartitions(Query<K,T> query)
          Partitions the given query and returns a list of PartitionQuerys, which will execute on local data.

Class<T> getPersistentClass()
          Returns the class of the persistent objects

String getSchemaName()
          Returns the schema name given to this DataStore

void initialize(Class<K> keyClass, Class<T> persistentClass, Properties properties)
          Initializes this DataStore.

K newKey()
          Returns a new instance of the key object.

T newPersistent()
          Returns a new instance of the managed persistent object.

Query<K,T> newQuery()
          Constructs and returns a new Query.

void put(K key, T obj)
          Inserts the persistent object with the given key.

void readFields(DataInput in)


boolean schemaExists()
          Returns whether the schema that holds the data exists in the datastore.

void setBeanFactory(BeanFactory<K,T> beanFactory)
          Sets the BeanFactory to use by the DataStore.

void setConf(org.apache.hadoop.conf.Configuration conf)


void setKeyClass(Class<K> keyClass)
          Sets the class of the keys

void setPersistentClass(Class<T> persistentClass)
          Sets the class of the persistent objects

void truncateSchema()
          Deletes all the data associated with the schema, but keeps the schema (table or similar) intact.

void write(DataOutput out)

Method Summary
`void`	`close()` Close the DataStore.
`void`	`createSchema()` Creates the optional schema or table (or similar) in the datastore to hold the objects.
`boolean`	`delete(K key)` Deletes the object with the given key
`long`	`deleteByQuery(Query<K,T> query)` Deletes all the objects matching the query.
`void`	`deleteSchema()` Deletes the underlying schema or table (or similar) in the datastore that holds the objects.
`Result<K,T>`	`execute(Query<K,T> query)` Executes the given query and returns the results.
`void`	`flush()` Forces the write caches to be flushed.
`T`	`get(K key)` Returns the object corresponding to the given key fetching all the fields.
`T`	`get(K key, String[] fields)` Returns the object corresponding to the given key.
`BeanFactory<K,T>`	`getBeanFactory()` Returns the BeanFactory used by the DataStore
`org.apache.hadoop.conf.Configuration`	`getConf()`
`Class<K>`	`getKeyClass()` Returns the class of the keys
`List<PartitionQuery<K,T>>`	`getPartitions(Query<K,T> query)` Partitions the given query and returns a list of `PartitionQuery`s, which will execute on local data.
`Class<T>`	`getPersistentClass()` Returns the class of the persistent objects
`String`	`getSchemaName()` Returns the schema name given to this DataStore
`void`	`initialize(Class<K> keyClass, Class<T> persistentClass, Properties properties)` Initializes this DataStore.
`K`	`newKey()` Returns a new instance of the key object.
`T`	`newPersistent()` Returns a new instance of the managed persistent object.
`Query<K,T>`	`newQuery()` Constructs and returns a new Query.
`void`	`put(K key, T obj)` Inserts the persistent object with the given key.
`void`	`readFields(DataInput in)`
`boolean`	`schemaExists()` Returns whether the schema that holds the data exists in the datastore.
`void`	`setBeanFactory(BeanFactory<K,T> beanFactory)` Sets the `BeanFactory` to use by the DataStore.
`void`	`setConf(org.apache.hadoop.conf.Configuration conf)`
`void`	`setKeyClass(Class<K> keyClass)` Sets the class of the keys
`void`	`setPersistentClass(Class<T> persistentClass)` Sets the class of the persistent objects
`void`	`truncateSchema()` Deletes all the data associated with the schema, but keeps the schema (table or similar) intact.
`void`	`write(DataOutput out)`

Method Detail

initialize

void initialize(Class<K> keyClass,
                Class<T> persistentClass,
                Properties properties)
                throws IOException

Initializes this DataStore.

Parameters:: keyClass - the class of the keys; persistentClass - the class of the persistent objects; properties - extra metadata
Throws:: IOException

setKeyClass

void setKeyClass(Class<K> keyClass)

Sets the class of the keys

Parameters:: keyClass - the class of keys

getKeyClass

Class<K> getKeyClass()

Returns the class of the keys

Returns:: class of the keys

setPersistentClass

void setPersistentClass(Class<T> persistentClass)

Sets the class of the persistent objects

Parameters:: persistentClass - class of persistent objects

getPersistentClass

Class<T> getPersistentClass()

Returns the class of the persistent objects

Returns:: class of the persistent objects

getSchemaName

String getSchemaName()

Returns the schema name given to this DataStore

Returns:: schema name

createSchema

void createSchema()
                  throws IOException

Creates the optional schema or table (or similar) in the datastore to hold the objects. If the schema is already created previously, or the underlying data model does not support or need this operation, the operation is ignored.

Throws:: IOException

deleteSchema

void deleteSchema()
                  throws IOException

Deletes the underlying schema or table (or similar) in the datastore that holds the objects. This also deletes all the data associated with the schema.

Throws:: IOException

truncateSchema

void truncateSchema()
                    throws IOException

Deletes all the data associated with the schema, but keeps the schema (table or similar) intact.

Throws:: IOException

schemaExists

boolean schemaExists()
                     throws IOException

Returns whether the schema that holds the data exists in the datastore.

Returns:: whether schema exists
Throws:: IOException

newKey

K newKey()
         throws IOException

Returns a new instance of the key object. If the object cannot be instantiated (it the class is a Java primitive wrapper, or does not have no-arg constructor) it throws an exception. Only use this function if you can make sure that the key class has a no-arg constructor.

Returns:: a new instance of the key object.
Throws:: IOException

newPersistent

T newPersistent()
                                   throws IOException

Returns a new instance of the managed persistent object.

Returns:: a new instance of the managed persistent object.
Throws:: IOException

get

T get(K key)
                         throws IOException

Returns the object corresponding to the given key fetching all the fields.

Parameters:: key - the key of the object
Returns:: the Object corresponding to the key or null if it cannot be found
Throws:: IOException

get

T get(K key,
      String[] fields)
                         throws IOException

Returns the object corresponding to the given key.

Parameters:: key - the key of the object; fields - the fields required in the object. Pass null, to retrieve all fields
Returns:: the Object corresponding to the key or null if it cannot be found
Throws:: IOException

put

void put(K key,
         T obj)
         throws IOException

Inserts the persistent object with the given key. If an object with the same key already exists it will silently be replaced. See also the note on visibility.

Throws:: IOException

delete

boolean delete(K key)
               throws IOException

Deletes the object with the given key

Parameters:: key - the key of the object
Returns:: whether the object was successfully deleted
Throws:: IOException

deleteByQuery

long deleteByQuery(Query<K,T> query)
                   throws IOException

Deletes all the objects matching the query. See also the note on visibility.

Parameters:: query - matching records to this query will be deleted
Returns:: number of deleted records
Throws:: IOException

execute

Result<K,T> execute(Query<K,T> query)
                                       throws IOException

Executes the given query and returns the results.

Parameters:: query - the query to execute.
Returns:: the results as a Result object.
Throws:: IOException

newQuery

Query<K,T> newQuery()

Constructs and returns a new Query.

Returns:: a new Query.

getPartitions

List<PartitionQuery<K,T>> getPartitions(Query<K,T> query)
                                                           throws IOException

Partitions the given query and returns a list of PartitionQuerys, which will execute on local data.

Parameters:: query - the base query to create the partitions for. If the query is null, then the data store returns the partitions for the default query (returning every object)
Returns:: a List of PartitionQuery's
Throws:: IOException

flush

void flush()
           throws IOException

Forces the write caches to be flushed. DataStore implementations may optimize their writing by deferring the actual put / delete operations until this moment. See also the note on visibility.

Throws:: IOException

setBeanFactory

void setBeanFactory(BeanFactory<K,T> beanFactory)

Sets the BeanFactory to use by the DataStore.

Parameters:: beanFactory - the BeanFactory to use

getBeanFactory

BeanFactory<K,T> getBeanFactory()

Returns the BeanFactory used by the DataStore

Returns:: the BeanFactory used by the DataStore

close

void close()
           throws IOException

Close the DataStore. This should release any resources held by the implementation, so that the instance is ready for GC. All other DataStore methods cannot be used after this method was called. Subsequent calls of this method are ignored.

Specified by:: close in interface Closeable

Throws:: IOException

getConf

org.apache.hadoop.conf.Configuration getConf()

Specified by:: getConf in interface org.apache.hadoop.conf.Configurable

setConf

void setConf(org.apache.hadoop.conf.Configuration conf)

Specified by:: setConf in interface org.apache.hadoop.conf.Configurable

readFields

void readFields(DataInput in)
                throws IOException

Specified by:: readFields in interface org.apache.hadoop.io.Writable

Throws:: IOException

write

void write(DataOutput out)
           throws IOException

Specified by:: write in interface org.apache.hadoop.io.Writable

Throws:: IOException