com.tangosol.util

Interface MapIndex<K,V,E>

Type Parameters:

K - the key type

V - the type of the value from which an extracted value is obtained

E - the type of the extracted value that is being indexed

All Known Implementing Classes:

ConditionalIndex, ForwardOnlyMapIndex, SimpleMapIndex

public interface MapIndex<K,V,E>

MapIndex is used to correlate values stored in an indexed Map (or attributes of those values) to the corresponding keys in the indexed Map.

Author:

cp/gg 2002.10.31

Field Summary

Fields

Modifier and Type	Field and Description
static Object	NO_VALUE Constant used to indicate that the index does not contain requested value.

Method Summary

Modifier and Type	Method and Description
void	delete(Map.Entry<? extends K,? extends V> entry) Update this index in response to a remove operation on a cache.
Object	get(K key) Using the index information if possible, get the value associated with the specified key.
Comparator<E>	getComparator() Get the Comparator used to sort the index.
Map<E,Set<K>>	getIndexContents() Get the Map that contains the index contents.
ValueExtractor<V,E>	getValueExtractor() Obtain the ValueExtractor object that the MapIndex uses to extract an indexable Object from a value stored in the indexed Map.
void	insert(Map.Entry<? extends K,? extends V> entry) Update this index in response to a insert operation on a cache.
boolean	isOrdered() Determine if the MapIndex orders the contents of the indexed information.
boolean	isPartial() Determine if indexed information for any entry in the indexed Map has been excluded from this index.
void	update(Map.Entry<? extends K,? extends V> entry) Update this index in response to an update operation on a cache.

Field Detail

NO_VALUE

static final Object NO_VALUE

Constant used to indicate that the index does not contain requested value.

Method Detail

getValueExtractor

ValueExtractor<V,E> getValueExtractor()

Obtain the ValueExtractor object that the MapIndex uses to extract an indexable Object from a value stored in the indexed Map. This property is never null.

Returns:

a ValueExtractor object, never null

isOrdered

boolean isOrdered()

Determine if the MapIndex orders the contents of the indexed information. To determine in which way the contents are ordered, get the Comparator from the index contents SortedMap object.

Returns:

true if the index contents are ordered, false otherwise

isPartial

boolean isPartial()

Determine if indexed information for any entry in the indexed Map has been excluded from this index. This information is used for IndexAwareFilter implementations to determine the most optimal way to apply the index.

Note: Queries that use a partial index are allowed not to return entries that are not indexed even though they would match the corresponding filter were they evaluated during the full scan (if there were no index). However, it's not allowable for a query to return entries that do not match the corresponding filter, regardless of their presence in the index.

Returns:

true if any entry of the indexed Map has been excluded from the index, false otherwise

Since:

Coherence 3.6

getIndexContents

Map<E,Set<K>> getIndexContents()

Get the Map that contains the index contents.

The keys of the Map are the return values from the ValueExtractor operating against the indexed Map's values, and for each key, the corresponding value stored in the Map is a Set of keys to the indexed Map.

If the MapIndex is known to be ordered, then the returned Map object will be an instance of SortedMap. The SortedMap may or may not have a Comparator object associated with it; see SortedMap.comparator().

A client should assume that the returned Map object is read-only and must not attempt to modify it.

Returns:

a Map (or a SortedMap) of the index contents

get

Object get(K key)

Using the index information if possible, get the value associated with the specified key. This is expected to be more efficient than using the ValueExtractor against an object containing the value, because the index should already have the necessary information at hand.

Parameters:

key - the key that specifies the object to extract the value from

Returns:

the value that would be extracted by this MapIndex's ValueExtractor from the object specified by the passed key; NO_VALUE if the index does not have the necessary information

getComparator

Comparator<E> getComparator()

Get the Comparator used to sort the index.

Returns:

the comparator

Since:

Coherence 3.5

insert

void insert(Map.Entry<? extends K,? extends V> entry)

Update this index in response to a insert operation on a cache.

Parameters:

entry - the entry representing the object being inserted

Since:

Coherence 3.5

update

void update(Map.Entry<? extends K,? extends V> entry)

Update this index in response to an update operation on a cache.

Parameters:

entry - the entry representing the object being updated

Since:

Coherence 3.5

delete

void delete(Map.Entry<? extends K,? extends V> entry)

Update this index in response to a remove operation on a cache.

Parameters:

entry - the entry representing the object being removed

Since:

Coherence 3.5