Utility routines which only read data can access databases which are currently being processed, parallel to the DBH.
The UDS online utility enables some functions to be executed online (i.e. during DBH operation) which would otherwise in some cases be implemented in a similar manner by other utility routines. The following functions which can modify a database or how it is processed are offered in the form of DMLs:
The online DML RELOCATE relocates records and tables in order to increase the occupation ratio of the data pages. Furthermore, you can relieve the load on a realm by relocating the pages of a distributable list to another realm.
The online DML FPASCAN offers an option to immediately reuse free space which, for example, is released when records or tables are deleted.
The online DML PREFRLM changes the setting of the preferred realm for a distributable list. When storing member records of this distributable list, the DBH searches in this realm for free pages at the lowest table level (level 0).
A detailed description of the UDS online utility is provided in the "Creation and Restructuring" manual).
The utility routine ONLINE-PRIVACY, which connects to the independent DBH like a normal application program, can dynamically modify access rights in the current session (see manual "Creation and Restructuring", ONLINE-PRIVACY).
Restrictions to database operation resulting from time spent checking the physical consistency of a database, can be reduced considerably by using the utility routine BCHECK to perform a precautionary physical consistency check on a consistent copy of the database. The final physical consistency database check can then be performed incrementally against the consistent and checked copy of the database. In this way, only data which has been modified since the preliminary check is included in the check, and the runtime of the check is significantly less than it would be with a complete check.
The utility routine UDSMON, integrated in UDS/SQL, enables a range of information to be queried regarding current database operation, including the status of currently executed transactions. This information enables special operations to be performed specifically at times when there is a low volume of DMLs and transactions.
A more extensive reorganisation of the data and modifications to the data structures can generally only be performed offline. In order to keep the runtime of such operations as low as possible, the utility routines use a number of optimizations which would be impossible for parallel DBH operation. Due also to the generally high level of complexity of such modifications, priority is given in this instance to the higher reliability of offline operation, rather than to availability.