DatastoreService.KeyRangeState (Google App Engine API for Java)

com.google.appengine.api.datastore

Enum DatastoreService.KeyRangeState

    • Enum Constant Summary

      Enum Constants 
      Enum Constant and Description
      COLLISION
      Indicates that entities with keys inside the given KeyRange already exist and writing to this range will overwrite those entities.
      CONTENTION
      Indicates the given KeyRange is empty but the datastore's automatic ID allocator may assign new entities keys in this range.
      EMPTY
      Indicates the given KeyRange is empty and the datastore's automatic ID allocator will not assign keys in this range to new entities.

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method and Description
      static DatastoreService.KeyRangeState valueOf(java.lang.String name)
      Returns the enum constant of this type with the specified name.
      static DatastoreService.KeyRangeState[] values()
      Returns an array containing the constants of this enum type, in the order they are declared.

      • Methods inherited from class java.lang.Enum

        compareTo, equals, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

      • Methods inherited from class java.lang.Object

        getClass, notify, notifyAll, wait, wait, wait

    • Enum Constant Detail

      • EMPTY

        public static final DatastoreService.KeyRangeState EMPTY
        Indicates the given KeyRange is empty and the datastore's automatic ID allocator will not assign keys in this range to new entities.

      • CONTENTION

        public static final DatastoreService.KeyRangeState CONTENTION
        Indicates the given KeyRange is empty but the datastore's automatic ID allocator may assign new entities keys in this range. However it is safe to manually assign Keys in this range if either of the following is true:
        • No other request will insert entities with the same kind and parent as the given KeyRange until all entities with manually assigned keys from this range have been written.
        • Overwriting entities written by other requests with the same kind and parent as the given KeyRange is acceptable.

        The datastore's automatic ID allocator will not assign a key to a new entity that will overwrite an existing entity, so once the range is populated there will no longer be any contention.

      • COLLISION

        public static final DatastoreService.KeyRangeState COLLISION
        Indicates that entities with keys inside the given KeyRange already exist and writing to this range will overwrite those entities. Additionally the implications of CONTENTION apply. If overwriting entities that exist in this range is acceptable it is safe to use the given range.

        The datastore's automatic ID allocator will never assign a key to a new entity that will overwrite an existing entity so entities written by the user to this range will never be overwritten by an entity with an automatically assigned key.

    • Method Detail

      • values

        public static DatastoreService.KeyRangeState[] values()
        Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows: 
        for (DatastoreService.KeyRangeState c : DatastoreService.KeyRangeState.values())
    System.out.println(c);
        Returns:
        an array containing the constants of this enum type, in the order they are declared

      • valueOf

        public static DatastoreService.KeyRangeState valueOf(java.lang.String name)
        Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
        Parameters:
        name - the name of the enum constant to be returned.
        Returns:
        the enum constant with the specified name
        Throws:
        java.lang.IllegalArgumentException - if this enum type has no constant with the specified name
        java.lang.NullPointerException - if the argument is null