com.bigdata.rdf.lexicon

Class LexiconKeyOrder

java.lang.Object

com.bigdata.striterator.AbstractKeyOrder<BigdataValue>

com.bigdata.rdf.lexicon.LexiconKeyOrder

All Implemented Interfaces:

IKeyOrder<BigdataValue>

public class LexiconKeyOrder
extends AbstractKeyOrder<BigdataValue>

Natural index orders for the LexiconRelation.

Version:

$Id$

Author:

Bryan Thompson

Field Summary

Fields

Modifier and Type	Field and Description
static LexiconKeyOrder	BLOBS Keys are BlobIVs.
static LexiconKeyOrder	ID2TERM Keys are TermIds.
static int	SLOT_IV The positional index corresponding to the IV in a LexPredicate.
static int	SLOT_TERM The positional index corresponding to the BigdataValue in a LexPredicate.
static LexiconKeyOrder	TERM2ID Keys are RDF Values.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	appendKeyComponent(IKeyBuilder keyBuilder, int i, Object keyComponent) Encodes an value into the key.
Comparator<BigdataValue>	getComparator() Operation is not supported.
String	getIndexName() The base name for the index.
int	getKeyArity() Return the #of elements in the key for this natural order.
int	getKeyOrder(int keyPos) Return the index of the slot in the IPredicate which appears at the specified position in the key.
int	index() The integer used to represent the LexiconKeyOrder.
String	toString() Return getIndexName()'s value.
static LexiconKeyOrder	valueOf(int index) Returns the singleton corresponding to the index.

Methods inherited from class com.bigdata.striterator.AbstractKeyOrder

getFromKey, getKey, getToKey

Methods inherited from class java.lang.Object

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

Field Detail

TERM2ID

public static final transient LexiconKeyOrder TERM2ID

Keys are RDF Values. Values are TermIds. Note that the keys of this index CAN NOT be decoded (they are unicode sort keys).

ID2TERM

public static final transient LexiconKeyOrder ID2TERM

Keys are TermIds. Values are RDF Values (which MAY be stored on raw records, which is transparent to the user if it occurs).

BLOBS

public static final transient LexiconKeyOrder BLOBS

Keys are BlobIVs. Values are RDF Values which are typically stored on raw records.

The index whose keys are formed from the hash code of the RDF Value plus a counter (to break ties on the hash code). The IV for an entry in the TERMS index is formed by wrapping this key. The values are the RDF Values and are often represented by raw records on the backing Journal. This index is only used for "large" Values. Most RDF Values wind up inlined into the statement indices.

SLOT_TERM

public static final transient int SLOT_TERM

The positional index corresponding to the BigdataValue in a LexPredicate.

See Also:

Constant Field Values

SLOT_IV

public static final transient int SLOT_IV

The positional index corresponding to the IV in a LexPredicate.

See Also:

Constant Field Values

Method Detail

valueOf

public static LexiconKeyOrder valueOf(int index)

Returns the singleton corresponding to the index.

Parameters:

index - The index.

Returns:

The singleton LexiconKeyOrder having that index.

Throws:

IllegalArgumentException - if the index is not valid.

getIndexName

public String getIndexName()

The base name for the index.

toString

public String toString()

Return getIndexName()'s value.

Overrides:

toString in class Object

index

public int index()

The integer used to represent the LexiconKeyOrder.

getKeyArity

public final int getKeyArity()

Description copied from interface: IKeyOrder

Return the #of elements in the key for this natural order.

getKeyOrder

public final int getKeyOrder(int keyPos)

Description copied from interface: IKeyOrder

Return the index of the slot in the IPredicate which appears at the specified position in the key.

Parameters:

keyPos - The index into the key that is being generated.

Returns:

The index of the slot in the IPredicate.

getComparator

public final Comparator<BigdataValue> getComparator()

Operation is not supported.

Note: The TERMS index key order is defined by the BlobIV keys. They are formed from the VTE, the hashCode (of the BigdataValue), and a collision counter. The collision counter is not known unless you actually scan the collision bucket in the TERMS index. So there is no way to provide a comparator for the TERMS index unless all of the BigdataValues have been resolved to their BlobIVs.

Throws:

UnsupportedOperationException

appendKeyComponent

protected void appendKeyComponent(IKeyBuilder keyBuilder,
                      int i,
                      Object keyComponent)

Encodes an value into the key. This implementation uses the default behavior of IKeyBuilder. If you need to specialize how a value gets encoded into the key then you can override this method.

Overridden to handle the encoding of the IV for the index.

Overrides:

appendKeyComponent in class AbstractKeyOrder<BigdataValue>