Ingres 9.2 Migration Guide - Actian

Large File SupportLarge File SupportA major enhancement to Ingres II 2.5 on operating systems that support 64­bit file systems is the ability to support file sizes greater than 2 GB. Thismeans that larger table, dump, work, journal, and checkpoint files can beaccommodated in a single location. It also removes the 2 GB limit on the sizeof the transaction log file.Large CatalogsIn this release, system catalogs can use pages larger than 2 KB. As a result,the user does not have to configure a 2 KB cache size in the DBMS for systemcatalogs.Row Locking for System CatalogsFor improved concurrency, the Ingres II 2.5 DBMS automatically uses rowlocking on system catalogs when catalogs are created using pages larger than2 KB. This feature is keyed from the system default page size, which isconfigurable through Configuration-By-Forms or Configuration Manager.Createdb creates a database with system catalogs that have the default pagesize. Running sysmod on an existing database, however, does notautomatically convert the system catalogs to use the default page size. Theuser must use the “with page_size” keyword to achieve this.Update Mode LockingPrior to Ingres II 2.5, when the DBMS fetched a row for a cursor mode update,it would acquire an exclusive lock. In serializable mode, this lock would be helduntil the end of transaction, even when the row was not updated. In thisrelease, the Ingres DBMS acquires an update mode lock for the row that is acandidate for update. If the row is actually updated, the update mode lock isconverted to logical exclusive lock; otherwise, it is converted down to sharedlock or released, depending on the current isolation level. Update mode lockingis now the default for cursor updates.218 Migration Guide