Package com.sleepycat.persist

Class PrimaryIndex<PK,E>

java.lang.Object
com.sleepycat.persist.PrimaryIndex<PK,E>
All Implemented Interfaces:
EntityIndex<PK,E>
public class PrimaryIndex<PK,E> extends Object
The primary index for an entity class and its primary key.

PrimaryIndex objects are thread-safe. Multiple threads may safely call the methods of a shared PrimaryIndex object.

PrimaryIndex implements EntityIndex to map the primary key type (PK) to the entity type (E).

The Entity annotation may be used to define an entity class and the PrimaryKey annotation may be used to define a primary key as shown in the following example.

 @Entity
 class Employee {

     @PrimaryKey
     long id;

     String name;

     Employee(long id, String name) {
         this.id = id;
         this.name = name;
     }

     private Employee() {} // For bindings
 }

To obtain the PrimaryIndex for a given entity class, call EntityStore.getPrimaryIndex, passing the primary key class and the entity class. For example:

 EntityStore store = new EntityStore(...);

 PrimaryIndex<Long, Employee> primaryIndex =
     store.getPrimaryIndex(Long.class, Employee.class);

Note that Long.class is passed as the primary key class, but the primary key field has the primitive type long. When a primitive primary key field is used, the corresponding primitive wrapper class is used to access the primary index. For more information on key field types, see PrimaryKey.

The PrimaryIndex provides the primary storage and access methods for the instances of a particular entity class. Entities are inserted and updated in the PrimaryIndex by calling a method in the family of put(E) methods. The put(E) method will insert the entity if no entity with the same primary key already exists. If an entity with the same primary key does exist, it will update the entity and return the existing (old) entity. For example:

 Employee oldEntity;
 oldEntity = primaryIndex.put(new Employee(1, "Jane Smith"));    // Inserts an entity
 assert oldEntity == null;
 oldEntity = primaryIndex.put(new Employee(2, "Joan Smith"));    // Inserts an entity
 assert oldEntity == null;
 oldEntity = primaryIndex.put(new Employee(2, "Joan M. Smith")); // Updates an entity
 assert oldEntity != null;

The putNoReturn(E) method can be used to avoid the overhead of returning the existing entity, when the existing entity is not important to the application. The return type of putNoReturn(E) is void. For example:

 primaryIndex.putNoReturn(new Employee(1, "Jane Smith"));    // Inserts an entity
 primaryIndex.putNoReturn(new Employee(2, "Joan Smith"));    // Inserts an entity
 primaryIndex.putNoReturn(new Employee(2, "Joan M. Smith")); // Updates an entity

The putNoOverwrite(E) method can be used to ensure that an existing entity is not overwritten. putNoOverwrite(E) returns true if the entity was inserted, or false if an existing entity exists and no action was taken. For example:

 boolean inserted;
 inserted = primaryIndex.putNoOverwrite(new Employee(1, "Jane Smith"));    // Inserts an entity
 assert inserted;
 inserted = primaryIndex.putNoOverwrite(new Employee(2, "Joan Smith"));    // Inserts an entity
 assert inserted;
 inserted = primaryIndex.putNoOverwrite(new Employee(2, "Joan M. Smith")); // No action was taken!
 assert !inserted;

Primary key values must be unique, in other words, each instance of a given entity class must have a distinct primary key value. Rather than assigning the unique primary key values yourself, a sequence can be used to assign sequential integer values automatically, starting with the value 1 (one). A sequence is defined using the PrimaryKey.sequence() annotation property. For example:

 @Entity
 class Employee {

     @PrimaryKey(sequence="ID")
     long id;

     String name;

     Employee(String name) {
         this.name = name;
     }

     private Employee() {} // For bindings
 }

The name of the sequence used above is "ID". Any name can be used. If the same sequence name is used in more than one entity class, the sequence will be shared by those classes, in other words, a single sequence of integers will be used for all instances of those classes. See PrimaryKey.sequence() for more information.

Any method in the family of put(E) methods may be used to insert entities where the primary key is assigned from a sequence. When the put(E) method returns, the primary key field of the entity object will be set to the assigned key value. For example:

 Employee employee;
 employee = new Employee("Jane Smith");
 primaryIndex.putNoReturn(employee);    // Inserts an entity
 assert employee.id == 1;
 employee = new Employee("Joan Smith");
 primaryIndex.putNoReturn(employee);    // Inserts an entity
 assert employee.id == 2;

This begs the question: How do you update an existing entity, without assigning a new primary key? The answer is that the put(E) methods will only assign a new key from the sequence if the primary key field is zero or null (for reference types). If an entity with a non-zero and non-null key field is passed to a put(E) method, any existing entity with that primary key value will be updated. For example:

 Employee employee;
 employee = new Employee("Jane Smith");
 primaryIndex.putNoReturn(employee);    // Inserts an entity
 assert employee.id == 1;
 employee = new Employee("Joan Smith");
 primaryIndex.putNoReturn(employee);    // Inserts an entity
 assert employee.id == 2;
 employee.name = "Joan M. Smith";
 primaryIndex.putNoReturn(employee);    // Updates an existing entity
 assert employee.id == 2;

Since PrimaryIndex implements the EntityIndex interface, it shares the common index methods for retrieving and deleting entities, opening cursors and using transactions. See EntityIndex for more information on these topics.

Note that when using an index, keys and values are stored and retrieved by value not by reference. In other words, if an entity object is stored and then retrieved, or retrieved twice, each object will be a separate instance. For example, in the code below the assertion will always fail.

 MyKey key = ...;
 MyEntity entity1 = new MyEntity(key, ...);
 index.put(entity1);
 MyEntity entity2 = index.get(key);
 assert entity1 == entity2; // always fails!

  • Constructor Details

    • PrimaryIndex

      public PrimaryIndex(Database database, Class<PK> keyClass, EntryBinding<PK> keyBinding, Class<E> entityClass, EntityBinding<E> entityBinding) throws DatabaseException
      Creates a primary index without using an EntityStore.

      This constructor is not normally needed and is provided for applications that wish to use custom bindings along with the Direct Persistence Layer. Normally, getPrimaryIndex is used instead.

      Note that when this constructor is used directly, primary keys cannot be automatically assigned from a sequence. The key assignment feature requires knowledge of the primary key field, which is only available if an EntityStore is used. Of course, primary keys may be assigned from a sequence manually before calling the put methods in this class.

      Parameters:
      database - the primary database.
      keyClass - the class of the primary key.
      keyBinding - the binding to be used for primary keys.
      entityClass - the class of the entities stored in this index.
      entityBinding - the binding to be used for entities.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

  • Method Details

    • getDatabase

      public Database getDatabase()
      Returns the underlying database for this index.
      Returns:
      the database.

    • getKeyClass

      public Class<PK> getKeyClass()
      Returns the primary key class for this index.
      Returns:
      the key class.

    • getKeyBinding

      public EntryBinding<PK> getKeyBinding()
      Returns the primary key binding for this index.
      Returns:
      the key binding.

    • getEntityClass

      public Class<E> getEntityClass()
      Returns the entity class for this index.
      Returns:
      the entity class.

    • getEntityBinding

      public EntityBinding<E> getEntityBinding()
      Returns the entity binding for this index.
      Returns:
      the entity binding.

    • put

      public E put(E entity) throws DatabaseException
      Inserts an entity and returns null, or updates it if the primary key already exists and returns the existing entity.

      If a PrimaryKey.sequence() is used and the primary key field of the given entity is null or zero, this method will assign the next value from the sequence to the primary key field of the given entity.

      Auto-commit is used implicitly if the store is transactional.

      Parameters:
      entity - the entity to be inserted or updated.
      Returns:
      the existing entity that was updated, or null if the entity was inserted.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • put

      public E put(Transaction txn, E entity) throws DatabaseException
      Inserts an entity and returns null, or updates it if the primary key already exists and returns the existing entity.

      If a PrimaryKey.sequence() is used and the primary key field of the given entity is null or zero, this method will assign the next value from the sequence to the primary key field of the given entity.

      Parameters:
      txn - the transaction used to protect this operation, null to use auto-commit, or null if the store is non-transactional.
      entity - the entity to be inserted or updated.
      Returns:
      the existing entity that was updated, or null if the entity was inserted.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • putNoReturn

      public void putNoReturn(E entity) throws DatabaseException
      Inserts an entity, or updates it if the primary key already exists (does not return the existing entity). This method may be used instead of put(Object) to save the overhead of returning the existing entity.

      If a PrimaryKey.sequence() is used and the primary key field of the given entity is null or zero, this method will assign the next value from the sequence to the primary key field of the given entity.

      Auto-commit is used implicitly if the store is transactional.

      Parameters:
      entity - the entity to be inserted or updated.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • putNoReturn

      public void putNoReturn(Transaction txn, E entity) throws DatabaseException
      Inserts an entity, or updates it if the primary key already exists (does not return the existing entity). This method may be used instead of put(Transaction,Object) to save the overhead of returning the existing entity.

      If a PrimaryKey.sequence() is used and the primary key field of the given entity is null or zero, this method will assign the next value from the sequence to the primary key field of the given entity.

      Parameters:
      txn - the transaction used to protect this operation, null to use auto-commit, or null if the store is non-transactional.
      entity - the entity to be inserted or updated.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • putNoOverwrite

      public boolean putNoOverwrite(E entity) throws DatabaseException
      Inserts an entity and returns true, or returns false if the primary key already exists.

      If a PrimaryKey.sequence() is used and the primary key field of the given entity is null or zero, this method will assign the next value from the sequence to the primary key field of the given entity.

      Auto-commit is used implicitly if the store is transactional.

      Parameters:
      entity - the entity to be inserted.
      Returns:
      true if the entity was inserted, or false if an entity with the same primary key is already present.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • putNoOverwrite

      public boolean putNoOverwrite(Transaction txn, E entity) throws DatabaseException
      Inserts an entity and returns true, or returns false if the primary key already exists.

      If a PrimaryKey.sequence() is used and the primary key field of the given entity is null or zero, this method will assign the next value from the sequence to the primary key field of the given entity.

      Parameters:
      txn - the transaction used to protect this operation, null to use auto-commit, or null if the store is non-transactional.
      entity - the entity to be inserted.
      Returns:
      true if the entity was inserted, or false if an entity with the same primary key is already present.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • get

      public E get(PK key) throws DatabaseException
      Description copied from interface: EntityIndex
      Gets an entity via a key of this index.

      The operation will not be transaction protected, and LockMode.DEFAULT is used implicitly.

      Parameters:
      key - the key to search for.
      Returns:
      the value mapped to the given key, or null if the key is not present in the index.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • get

      public E get(Transaction txn, PK key, LockMode lockMode) throws DatabaseException
      Description copied from interface: EntityIndex
      Gets an entity via a key of this index.
      Parameters:
      txn - the transaction used to protect this operation, or null if the operation should not be transaction protected.
      key - the key to search for.
      lockMode - the lock mode to use for this operation, or null to use LockMode.DEFAULT.
      Returns:
      the value mapped to the given key, or null if the key is not present in the index.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • map

      public Map<PK,E> map()
      Description copied from interface: EntityIndex
      Returns a standard Java map based on this entity index. The StoredMap returned is defined by the Collections API. Stored collections conform to the standard Java collections framework interface.
      Returns:
      the map.

    • sortedMap

      public SortedMap<PK,E> sortedMap()
      Description copied from interface: EntityIndex
      Returns a standard Java sorted map based on this entity index. The StoredSortedMap returned is defined by the Collections API. Stored collections conform to the standard Java collections framework interface.
      Returns:
      the map.

    • contains

      public boolean contains(PK key) throws DatabaseException
      Description copied from interface: EntityIndex
      Checks for existence of a key in this index.

      The operation will not be transaction protected, and LockMode.DEFAULT is used implicitly.

      Specified by:
      contains in interface EntityIndex<K,E>
      Parameters:
      key - the key to search for.
      Returns:
      whether the key exists in the index.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • contains

      public boolean contains(Transaction txn, PK key, LockMode lockMode) throws DatabaseException
      Description copied from interface: EntityIndex
      Checks for existence of a key in this index.
      Specified by:
      contains in interface EntityIndex<K,E>
      Parameters:
      txn - the transaction used to protect this operation, or null if the operation should not be transaction protected.
      key - the key to search for.
      lockMode - the lock mode to use for this operation, or null to use LockMode.DEFAULT.
      Returns:
      whether the key exists in the index.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • count

      public long count() throws DatabaseException
      Description copied from interface: EntityIndex
      Returns a non-transactional count of the entities in this index.

      This operation is faster than obtaining a count by scanning the index manually, and will not perturb the current contents of the cache. However, the count is not guaranteed to be accurate if there are concurrent updates. Note that this method does scan a significant portion of the index and should be considered a fairly expensive operation.

      Specified by:
      count in interface EntityIndex<K,E>
      Returns:
      the number of entities in this index.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • delete

      public boolean delete(PK key) throws DatabaseException
      Description copied from interface: EntityIndex
      Deletes all entities with a given index key.

      Auto-commit is used implicitly if the store is transactional.

      Specified by:
      delete in interface EntityIndex<K,E>
      Parameters:
      key - the key to search for.
      Returns:
      whether any entities were deleted.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • delete

      public boolean delete(Transaction txn, PK key) throws DatabaseException
      Description copied from interface: EntityIndex
      Deletes all entities with a given index key.
      Specified by:
      delete in interface EntityIndex<K,E>
      Parameters:
      txn - the transaction used to protect this operation, null to use auto-commit, or null if the store is non-transactional.
      key - the key to search for.
      Returns:
      whether any entities were deleted.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • keys

      public EntityCursor<PK> keys() throws DatabaseException
      Description copied from interface: EntityIndex
      Opens a cursor for traversing all keys in this index.

      The operations performed with the cursor will not be transaction protected, and CursorConfig.DEFAULT is used implicitly. If the store is transactional, the cursor may not be used to update or delete entities.

      Specified by:
      keys in interface EntityIndex<K,E>
      Returns:
      the cursor.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • keys

      public EntityCursor<PK> keys(Transaction txn, CursorConfig config) throws DatabaseException
      Description copied from interface: EntityIndex
      Opens a cursor for traversing all keys in this index.
      Specified by:
      keys in interface EntityIndex<K,E>
      Parameters:
      txn - the transaction used to protect all operations performed with the cursor, or null if the operations should not be transaction protected. If the store is non-transactional, null must be specified. For a transactional store the transaction is optional for read-only access and required for read-write access.
      config - the cursor configuration that determines the default lock mode used for all cursor operations, or null to implicitly use CursorConfig.DEFAULT.
      Returns:
      the cursor.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • entities

      public EntityCursor<E> entities() throws DatabaseException
      Description copied from interface: EntityIndex
      Opens a cursor for traversing all entities in this index.

      The operations performed with the cursor will not be transaction protected, and CursorConfig.DEFAULT is used implicitly. If the store is transactional, the cursor may not be used to update or delete entities.

      Specified by:
      entities in interface EntityIndex<K,E>
      Returns:
      the cursor.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • entities

      public EntityCursor<E> entities(Transaction txn, CursorConfig config) throws DatabaseException
      Description copied from interface: EntityIndex
      Opens a cursor for traversing all entities in this index.
      Specified by:
      entities in interface EntityIndex<K,E>
      Parameters:
      txn - the transaction used to protect all operations performed with the cursor, or null if the operations should not be transaction protected. If the store is non-transactional, null must be specified. For a transactional store the transaction is optional for read-only access and required for read-write access.
      config - the cursor configuration that determines the default lock mode used for all cursor operations, or null to implicitly use CursorConfig.DEFAULT.
      Returns:
      the cursor.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • keys

      public EntityCursor<PK> keys(PK fromKey, boolean fromInclusive, PK toKey, boolean toInclusive) throws DatabaseException
      Description copied from interface: EntityIndex
      Opens a cursor for traversing keys in a key range.

      The operations performed with the cursor will not be transaction protected, and CursorConfig.DEFAULT is used implicitly. If the store is transactional, the cursor may not be used to update or delete entities.

      Specified by:
      keys in interface EntityIndex<K,E>
      Parameters:
      fromKey - is the lower bound of the key range, or null if the range has no lower bound.
      fromInclusive - is true if keys greater than or equal to fromKey should be included in the key range, or false if only keys greater than fromKey should be included.
      toKey - is the upper bound of the key range, or null if the range has no upper bound.
      toInclusive - is true if keys less than or equal to toKey should be included in the key range, or false if only keys less than toKey should be included.
      Returns:
      the cursor.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • keys

      public EntityCursor<PK> keys(Transaction txn, PK fromKey, boolean fromInclusive, PK toKey, boolean toInclusive, CursorConfig config) throws DatabaseException
      Description copied from interface: EntityIndex
      Opens a cursor for traversing keys in a key range.
      Specified by:
      keys in interface EntityIndex<K,E>
      Parameters:
      txn - the transaction used to protect all operations performed with the cursor, or null if the operations should not be transaction protected. If the store is non-transactional, null must be specified. For a transactional store the transaction is optional for read-only access and required for read-write access.
      fromKey - is the lower bound of the key range, or null if the range has no lower bound.
      fromInclusive - is true if keys greater than or equal to fromKey should be included in the key range, or false if only keys greater than fromKey should be included.
      toKey - is the upper bound of the key range, or null if the range has no upper bound.
      toInclusive - is true if keys less than or equal to toKey should be included in the key range, or false if only keys less than toKey should be included.
      config - the cursor configuration that determines the default lock mode used for all cursor operations, or null to implicitly use CursorConfig.DEFAULT.
      Returns:
      the cursor.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • entities

      public EntityCursor<E> entities(PK fromKey, boolean fromInclusive, PK toKey, boolean toInclusive) throws DatabaseException
      Description copied from interface: EntityIndex
      Opens a cursor for traversing entities in a key range.

      The operations performed with the cursor will not be transaction protected, and CursorConfig.DEFAULT is used implicitly. If the store is transactional, the cursor may not be used to update or delete entities.

      Specified by:
      entities in interface EntityIndex<K,E>
      Parameters:
      fromKey - is the lower bound of the key range, or null if the range has no lower bound.
      fromInclusive - is true if keys greater than or equal to fromKey should be included in the key range, or false if only keys greater than fromKey should be included.
      toKey - is the upper bound of the key range, or null if the range has no upper bound.
      toInclusive - is true if keys less than or equal to toKey should be included in the key range, or false if only keys less than toKey should be included.
      Returns:
      the cursor.
      Throws:
      DatabaseException - the base class for all BDB exceptions.

    • entities

      public EntityCursor<E> entities(Transaction txn, PK fromKey, boolean fromInclusive, PK toKey, boolean toInclusive, CursorConfig config) throws DatabaseException
      Description copied from interface: EntityIndex
      Opens a cursor for traversing entities in a key range.
      Specified by:
      entities in interface EntityIndex<K,E>
      Parameters:
      txn - the transaction used to protect all operations performed with the cursor, or null if the operations should not be transaction protected. If the store is non-transactional, null must be specified. For a transactional store the transaction is optional for read-only access and required for read-write access.
      fromKey - is the lower bound of the key range, or null if the range has no lower bound.
      fromInclusive - is true if keys greater than or equal to fromKey should be included in the key range, or false if only keys greater than fromKey should be included.
      toKey - is the upper bound of the key range, or null if the range has no upper bound.
      toInclusive - is true if keys less than or equal to toKey should be included in the key range, or false if only keys less than toKey should be included.
      config - the cursor configuration that determines the default lock mode used for all cursor operations, or null to implicitly use CursorConfig.DEFAULT.
      Returns:
      the cursor.
      Throws:
      DatabaseException - the base class for all BDB exceptions.