Fast Building of Collections

You can move the building or rebuilding of some ObjectSet and MemberKeyDictionary collections from the Relationship Maintenance phase to the Object Conversion phase of the reorganization process, by setting the FastBuildBTreeCollections parameter in the [JadeReorg] section of the JADE initialization file to true.

Fast building of collections significantly reduces the elapsed time of large database reorganizations involving collection maintenance, by using a faster extract, sort, and build algorithm and by allowing the collection maintenance to be performed in parallel by multiple reorganization workers using much less random I/O activity.

Fast building of collections is available only for non-updating reorganizations. If you enable fast building of collections, you must disallow updates when you initiate the reorganization, as follows.

• In the JADE development environment, the Allow updates check box on the Classes Needing Reorg dialog is disabled and unselected.

• When loading a schema using the batch jadloadb utility, specify reorgAllowUpdates=false on the command line.

• When carrying out a reorganization using the non-GUI jadclient application with app= JadeReorgApp, specify reorgAllowUpdates=false on the command line.

Fast building or rebuilding of collections for a MemberKeyDictionary or ObjectSet reference occurs when the inverse is an existing object reference; that is, for a many-to-one relationship. The update mode of the collection reference must be automatic and that of the object reference must be manual. The ObjectSet reference includes subclasses of the collection class ObjectSet and subclasses of the collection class Set where the membership is a class. Member key dictionaries can have key paths and collection references with constraint methods.

Fast building of collections can be invoked for the following structural changes.

• An inverse is established between an existing MemberKeyDictionary or ObjectSet reference and an existing object reference.

• A MemberKeyDictionary or ObjectSet reference is added for an existing object reference inverse.

• The key definition of a MemberKeyDictionary reference is changed; for example, if:

  • Key elements are added, deleted, or reordered

  • The Sort Order, Case Insensitive, or Descending property of a key element is changed

• The constraint method of a MemberKeyDictionary reference is changed.

• A MemberKeyDictionary or ObjectSet class structure is changed; for example, the Entries Per Block property on the Tuning sheet.

Fast building of collections is not allowed when:

• The collection owner class is a subclass of JadeBytes.

• The collection membership is the JadeBytes class or a subclass.

• The object reference property is new and therefore has the initial default value of null.

  If the inverse collection reference exists and is not empty, the offline collection builder populates the new reference property.

• The membership of the collection is not a class; for example, an ObjectSet with an interface as its membership.

• The collection reference has one or more inverses declared that are collections.

By default, the extract and sort files are placed in the database directory (that is, the directory containing the database control file). You can specify another location by using the ReorgSortDirectory parameter in the [JadeReorg] section of the JADE initialization file.

The dictionary key sort uses up to 50M bytes of memory for each reorganization worker, by default. You can increase the amount of sort memory to improve the sort performance when the total key length exceeds 30 bytes, using the WorkerSortMemory parameter in the [JadeReorg] section of the JADE initialization file.

Fast-built collections are densely packed, leaving two free entries in each block which gives an approximate load factor of 98 percent. For new collections, user-coded constructors are not executed and user-specified property values are initialized with null values. For existing collections that are rebuilt, user-specified property values are retained.

When a reorganization with the FastBuildBTreeCollections parameter set to true is replayed by a roll-forward recovery or on a secondary SDS or RPS node, the entire fast building process involving extracts, sorts, and builds does not occur. Instead, the collection headers and blocks audited during the original reorganization build jobs on the primary SDS node are applied from the journal by the reorganization worker after the objects have been converted and copied to the .reo files.