Discuss some types of database utilities and tools and their functions.

Other tools are often available to database designers, users, and DBAs. CASE tools are used in the design phase of database systems. Another tool that can be quite useful in large organizations is an expanded data dictionary (or data repository) system. In addition to storing catalog information about schemas and constraints, the data dictionary stores other information, such as design decisions, usage standards, application program descriptions, and user information. Such a system is also called an information repository.

This information can be accessed directly by users or the DBA when needed. A data dictionary utility is similar to the DBMS catalog, but it includes a wider variety of information and is accessed mainly by users rather than by the DBMS software.

Application development environments, such as the PowerBuilder (Sybase) or JBuilder (Borland) system, are becoming quite popular. These systems provide an environment for developing database applications and include facilities that help in many facets of database systems, including database design, CUI development, querying and updating, and application program development.'

In addition to possessing the software modules just described, most DBMSs have database utilities that help the DBA in managing the database system. Common utilities have the following types of functions:

• Loading: A loading utility is used to load existing data files-such as text files or sequential files-into the database. Usually, the current (source) format of the data tile and the desired (target) database file structure are specified to the utility, which then automatically reformats the data and stores it in the database. With the proliferation of DBMSs, transferring data from one DBMS to another is becoming common in many organizations. Some vendors are offering products that generate the appropriate loading programs, given the existing source and target database storage descriptions (internal schemas). Such tools are also called conversion tools

• Backup: A backup utility creates a backup copy of the database, usually by dumping the entire database onto tape. The backup copy can be used to restore the database in case of catastrophic failure. Incremental backups are also often used, where only changes since the previous backup are recorded. Incremental backup is more complex but saves space.

• File reorganization: This utility can be used to reorganize a database file into a different file organization to improve performance.

• Performance monitoring: Such a utility monitors database usage and provides statistics to the DBA. The DBA uses the statistics in making decisions such as whether or not to reorganize files to improve performance.

Other utilities may be available for sorting files, handling data compression, monitoring access by users, interfacing with the network, and performing other functions.