org.garret.perst
Interface FieldIndex

All Superinterfaces:

java.io.Externalizable, GenericIndex, IPersistent, IResource, ITable, java.io.Serializable

public interface FieldIndex

extends GenericIndex

Interface of indexed field. Index is used to provide fast access to the object by the value of indexed field. Objects in the index are stored ordered by the value of indexed field. It is possible to select object using exact value of the key or select set of objects which key belongs to the specified interval (each boundary can be specified or unspecified and can be inclusive or exclusive) Key should be of scalar, String, java.util.Date or peristent object type.

Field Summary

Fields inherited from interface org.garret.perst.GenericIndex

ASCENT_ORDER, DESCENT_ORDER

Method Summary

void	append(IPersistent obj) Assign to the integer indexed field unique autoicremented value and insert object in the index.
boolean	contains(IPersistent obj) Check if index contains object which is equal to the specified object.
boolean	containsObject(IPersistent obj) Check if index contains specified object instance.
java.lang.Class	getIndexedClass() Get class obejct objects which can be inserted in this index
java.lang.reflect.Field[]	getKeyFields() Get fields used as a key
boolean	put(IPersistent obj) Put new object in the index.
void	remove(IPersistent obj) Remove object from the index
IPersistent	remove(Key key) Remove object with specified key from the unique index
java.util.Iterator	select(java.lang.String predicate) Select members of the collection using search predicate.
IPersistent	set(IPersistent obj) Associate new object with the key specified by object field value.

Methods inherited from interface org.garret.perst.GenericIndex

clear, entryIterator, entryIterator, get, get, get, getKeyType, getKeyTypes, getPrefix, iterator, iterator, prefixIterator, prefixSearch, size, toPersistentArray, toPersistentArray

Methods inherited from interface org.garret.perst.IPersistent

assignOid, deallocate, getOid, getStorage, invalidate, isDeleted, isModified, isPersistent, isRaw, load, loadAndModify, makePersistent, modify, onLoad, onStore, recursiveLoading, store

Methods inherited from interface java.io.Externalizable

readExternal, writeExternal

Methods inherited from interface org.garret.perst.IResource

exclusiveLock, exclusiveLock, reset, sharedLock, sharedLock, unlock

Methods inherited from interface org.garret.perst.ITable

select

Method Detail

append

public void append(IPersistent obj)

Assign to the integer indexed field unique autoicremented value and insert object in the index.

Parameters:

obj - object to be inserted in index. Object should contain indexed field of integer (int or long) type. This field is assigned unique value (which will not be reused while this index exists) and object is marked as modified. Object can be not yet peristent, in this case its forced to become persistent by assigning OID to it.

Throws:

StorageError(StorageError.INCOMPATIBLE_KEY_TYPE) - when indexed field has type other than int or long

contains

public boolean contains(IPersistent obj)

Check if index contains object which is equal to the specified object. More formally, returns true if and only if this collection contains at least one element e such that (obj==null ? e==null : obj.equals(e)).

Parameters:

obj - object to be searched in the index. Object should contain indexed field.

Returns:

true if collection contains object equals to the specified

containsObject

public boolean containsObject(IPersistent obj)

Check if index contains specified object instance.

Parameters:

obj - object to be searched in the index. Object should contain indexed field.

Returns:

true if object is present in the index, false otherwise

getIndexedClass

public java.lang.Class getIndexedClass()

Get class obejct objects which can be inserted in this index

Returns:

class specified in Storage.createFielIndex method

getKeyFields

public java.lang.reflect.Field[] getKeyFields()

Get fields used as a key

Returns:

array of index key fields

put

public boolean put(IPersistent obj)

Put new object in the index.

Parameters:

obj - object to be inserted in index. Object should contain indexed field. Object can be not yet peristent, in this case its forced to become persistent by assigning OID to it.

Returns:

true if object is successfully inserted in the index, false if index was declared as unique and there is already object with such value of the key in the index.

remove

public void remove(IPersistent obj)

Remove object from the index

Parameters:

obj - object removed from the index. Object should contain indexed field.

Throws:

StorageError(StorageError.KEY_NOT_FOUND) - exception if there is no such key in the index

remove

public IPersistent remove(Key key)

Remove object with specified key from the unique index

Parameters:

key - value of removed key

Returns:

removed object

Throws:

StorageError(StorageError.KEY_NOT_FOUND) - exception if there is no such key in the index, or StorageError(StorageError.KEY_NOT_UNIQUE) if index is not unique.

select

public java.util.Iterator select(java.lang.String predicate)

Select members of the collection using search predicate. This iterator doesn't support remove() method. To make it possible to update, remove or add members to the index during iteration it is necessary to set "perst.concurrent.iterator" property (by default it is not supported because it cause extra overhead during iteration)

Parameters:

predicate - JSQL condition

Returns:

iterator through members of the collection matching search condition

set

public IPersistent set(IPersistent obj)

Associate new object with the key specified by object field value. If there is already object with such key in the index, then it will be removed from the index and new value associated with this key.

Parameters:

obj - object to be inserted in index. Object should contain indexed field. Object can be not yet peristent, in this case its forced to become persistent by assigning OID to it.

Returns:

object previously associated with this key, null if there was no such object