org.apache.mahout.cf.taste.impl.model.hbase

Class HBaseDataModel

java.lang.Object

org.apache.mahout.cf.taste.impl.model.hbase.HBaseDataModel

All Implemented Interfaces:

Closeable, Serializable, AutoCloseable, Refreshable, DataModel

public final class HBaseDataModel
extends Object
implements DataModel, Closeable

Naive approach of storing one preference as one value in the table. Preferences are indexed as (user, item) and (item, user) for O(1) lookups.

The default table name is "taste", this can be set through a constructor argument. Each row has a value starting with "i" or "u" followed by the actual id encoded as a big endian long.

E.g., "u\x00\x00\x00\x00\x00\x00\x04\xd2" is user 1234L

There are two column families: "users" and "items".

The "users" column family holds user->item preferences. Each userID is the column qualifier and the value is the preference.

The "items" column fmaily holds item->user preferences. Each itemID is the column qualifier and the value is the preference.

User IDs and item IDs are cached in a FastIDSet since it requires a full table scan to build these sets. Preferences are not cached since they are pretty cheap lookups in HBase (also caching the Preferences defeats the purpose of a scalable storage engine like HBase).

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
HBaseDataModel(org.apache.hadoop.hbase.client.HTablePool pool, String tableName, org.apache.hadoop.conf.Configuration conf)
HBaseDataModel(String zkConnect)
HBaseDataModel(String zkConnect, String tableName)

Method Summary

Methods

Modifier and Type	Method and Description
void	close()
LongPrimitiveIterator	getItemIDs()
FastIDSet	getItemIDsFromUser(long userID)
float	getMaxPreference()
float	getMinPreference()
int	getNumItems()
int	getNumUsers()
int	getNumUsersWithPreferenceFor(long itemID)
int	getNumUsersWithPreferenceFor(long itemID1, long itemID2)
PreferenceArray	getPreferencesForItem(long itemID)
PreferenceArray	getPreferencesFromUser(long userID)
Long	getPreferenceTime(long userID, long itemID)
Float	getPreferenceValue(long userID, long itemID)
String	getTableName()
LongPrimitiveIterator	getUserIDs()
boolean	hasPreferenceValues()
void	refresh(Collection<Refreshable> alreadyRefreshed)
void	removePreference(long userID, long itemID)
void	setPreference(long userID, long itemID, float value)

Methods inherited from class java.lang.Object

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

Constructor Detail

HBaseDataModel

public HBaseDataModel(String zkConnect)
               throws IOException

Throws:

IOException

HBaseDataModel

public HBaseDataModel(String zkConnect,
              String tableName)
               throws IOException

Throws:

IOException

HBaseDataModel

public HBaseDataModel(org.apache.hadoop.hbase.client.HTablePool pool,
              String tableName,
              org.apache.hadoop.conf.Configuration conf)
               throws IOException

Throws:

IOException

Method Detail

getTableName

public String getTableName()

getUserIDs

public LongPrimitiveIterator getUserIDs()

Specified by:

getUserIDs in interface DataModel

getPreferencesFromUser

public PreferenceArray getPreferencesFromUser(long userID)
                                       throws TasteException

Specified by:

getPreferencesFromUser in interface DataModel

Throws:

TasteException

getItemIDsFromUser

public FastIDSet getItemIDsFromUser(long userID)
                             throws TasteException

Specified by:

getItemIDsFromUser in interface DataModel

Throws:

TasteException

getItemIDs

public LongPrimitiveIterator getItemIDs()

Specified by:

getItemIDs in interface DataModel

getPreferencesForItem

public PreferenceArray getPreferencesForItem(long itemID)
                                      throws TasteException

Specified by:

getPreferencesForItem in interface DataModel

Throws:

TasteException

getPreferenceValue

public Float getPreferenceValue(long userID,
                       long itemID)
                         throws TasteException

Specified by:

getPreferenceValue in interface DataModel

Throws:

TasteException

getPreferenceTime

public Long getPreferenceTime(long userID,
                     long itemID)
                       throws TasteException

Specified by:

getPreferenceTime in interface DataModel

Throws:

TasteException

getNumItems

public int getNumItems()

Specified by:

getNumItems in interface DataModel

getNumUsers

public int getNumUsers()

Specified by:

getNumUsers in interface DataModel

getNumUsersWithPreferenceFor

public int getNumUsersWithPreferenceFor(long itemID)
                                 throws TasteException

Specified by:

getNumUsersWithPreferenceFor in interface DataModel

Throws:

TasteException

getNumUsersWithPreferenceFor

public int getNumUsersWithPreferenceFor(long itemID1,
                               long itemID2)
                                 throws TasteException

Specified by:

getNumUsersWithPreferenceFor in interface DataModel

Throws:

TasteException

setPreference

public void setPreference(long userID,
                 long itemID,
                 float value)
                   throws TasteException

Specified by:

setPreference in interface DataModel

Throws:

TasteException

removePreference

public void removePreference(long userID,
                    long itemID)
                      throws TasteException

Specified by:

removePreference in interface DataModel

Throws:

TasteException

hasPreferenceValues

public boolean hasPreferenceValues()

Specified by:

hasPreferenceValues in interface DataModel

getMaxPreference

public float getMaxPreference()

Specified by:

getMaxPreference in interface DataModel

getMinPreference

public float getMinPreference()

Specified by:

getMinPreference in interface DataModel

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

refresh

public void refresh(Collection<Refreshable> alreadyRefreshed)

Specified by:

refresh in interface Refreshable