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Database Documentation

Database documentation includes the recording of the procedures, standards, guidelines and database descriptions necessary for the proper, efficient and continuing use of the database.

The documentation must be specially prepared for and selectively distributed to

The DBA has the responsibility for providing and maintaining adequate documentation for these recipients. This chapter discusses the types of documentation that are required. The list given is not necessarily exhaustive.

This document covers the following topics:


Standards

Establish and maintain a consistent set of database controls, particularly in the following areas:

Some personnel will resist the establishment of standards for the database environment. Give careful consideration to the status of a standard and of areas where standards should be established. In general, a new standard will require negotiation, arbitration, and compromise before all the parties concerned will accept it even as a proposed standard. The only way to determine whether a standard is practical is to implement it.

Standards are subject to change. The process of changing an existing standard must be as tightly controlled as that of installing a new one. Changes should be formally proposed and communicated to all the affected users. After a trial period, review the proposed change with users to decide whether it should become a standard.

Periodically review the database standards to evaluate their effectiveness and to ensure that they are being followed. Corrective action may need to follow such a review. The DBA also has the principal responsibility for ensuring that all personnel who work in the database environment are aware of, and adequately trained in, the use of the standards.

Because each site has its own procedures and requirements, this documentation does not suggest a specific set of standards.

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Description of the Database

The database description should cover the following main areas:

In addition, the reasons why this particular implementation has been chosen should be recorded. This information will later prove useful when maintenance or new application design is undertaken.

The DBA is responsible for formally describing the database in the manner discussed above and maintaining this description on a data dictionary (whether this process is automated or not). The project team will be required to provide the DBA with all the information the DBA needs to perform this task.

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Data Dictionary, Function and Use

A data dictionary contains information about the definition, structure and use of data. It does not store the actual data itself, but rather data about data. Simply stated, the data dictionary contains the name of each data type (element), its definition (size and type), where and how it is used and its relationship to other data elements.

A data dictionary enables the DBA to exercise better management and control over the organization's data resources. Advanced users of data dictionaries have also found them to be valuable tools in project management and systems design.

The data dictionary will enable the DBA independently to manage actual data items and the programs that manipulate and access them. This independence of control results in the substantially enhanced usefulness of the data. The data dictionary serves to collect the information needed in order to make the data more useful.

Containing all of the definitions of the data, the dictionary becomes the information repository for the data's attributes, characteristics, sources, use, and interrelationships with other data. The data dictionary should provide the following information:

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Predict : The Adabas Data Dictionary

Predict, the Adabas data dictionary system, is used to establish and maintain an online data dictionary.

Database information may be entered into the dictionary in online or batch mode. The description of the data in the Adabas dictionary includes information about files, the fields defined for each file and the relationship between files. The description of use includes information about the owners and users of the data in addition to the systems, programs, modules and reports that use the data. Dictionary entries are provided for information about

Standard data dictionary reports may be used to

In addition, the dictionary data can also be accessed directly from Natural since it is stored in a standard Adabas file.

Refer to the Predict documentation for more detailed information about the Adabas data dictionary system.

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Applications Using the Database

For each application using the database, the following information should be recorded:

Since any database is only a partial implementation of the conceptual database (see previous section) and user's requirements change with time, new applications of the database will be found as time passes. Some of these applications may be developed into new systems or additions to existing systems, but they first arise as a simple user requirement .

Establish procedures for recording unplanned applications of the database; if one becomes relatively frequent or important, you can often gain a processing advantage by redesigning or reorganizing the database or files within it. For example, assume that a file was initially loaded in Customer Number order. Subsequently, applications that process the file by Salesman Number assume greater significance. You can unload the file and reload it in Salesman Number sequence without affecting the logical operation of most existing applications, thus achieving an overall reduction in the processing time needed by all the applications that use the file.

Records of this unplanned use of the database or shift of emphasis in processing priorities, can be made when a user makes an interactive request for information, whether the user does this in his or her own department or through the DBA. These records should be regularly reviewed by the DBA and discussed with the affected users.

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Description of Data Sources

For any new application, the data dictionary is the first reference document for determining the potential sources of information. The description of data sources will be derived during the systems analysis and design phases of a new project.

Record and retain the following information about each system:

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Data Access and Manipulation Procedures

The DBA must have administrative control over all access to and updating of the data in the database. Unless this is so, there can be little meaningful control or protection exercised over it. The lack of such control can result in serious security and integrity problems.

Because authority and responsibility for the database cross organizational boundaries, a corporate policy covering database usage by and among operating units should be published. Such policy statements can enhance the administrative control of the DBA and help to promote clear understanding of database procedures among users and data processing personnel.

Part of this policy will include statements on

This policy statement should be proposed and drafted by the DBA, and then reviewed and agreed upon by all the affected parties.

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Passwords and User Identification

User ID and password information needs to be stored securely by the DBA, as only the DBA and the affected users should have access to it. This documentation will include

Once this authority has been established, it is important to set up proper control procedures in order to ensure that violations of database security do not occur.

The DBA uses the Adabas Security utility to implement and control password security (see the Adabas Security documentation for more information). The DBA must be the only person at an installation who is permitted to use this utility.

The DBA must implement procedures to physically secure the security utility itself, and all documentation concerning security.

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Backup Procedures

The content of backup files, as either database or file copies (taken by the Adabas ADASAV utility) should be recorded together with the following information:

The DBA should help computer operations personnel to develop procedures for carrying out the database backup task. Database backup is an essential step in ensuring that the database can be restored to its proper state in the event of destruction or damage. The decision will have to be taken (for every application) as to whether the entire database is to be backed up or whether dumping and restoring of specific files is more appropriate.

Information about developing backup procedures for a particular application is included in the Adabas Operations documentation.

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Restart and Recovery Procedures

The DBA is responsible for formulating and supervising procedures for

Restart and recovery is an important database protection consideration. The DBA must develop standards, procedures and rules to provide such a capability. The DBA must be certain that the standards and rules are being adhered to and enforced. Restart and recovery must be planned for and designed in conjunction with the implementation of the DBMS. It should not be added as an afterthought.

Detailed information about Adabas restart and recovery is included in the Adabas Operations documentation.

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DBMS Performance and Measurement

The DBA has a continuing role in maintaining and improving the performance of the database system.

To do this, the DBA must monitor the performance of the system and try alternative design strategies to improve it. As work patterns change in the company, both the volume and relative proportion of types of transactions may change. This may affect performance and design changes may be necessary to counteract it.

In the longer term it may be possible to predict changes in workload, and plan how to meet them by redesign or equipment enhancement.

The effect of new hardware or software should also be evaluated, and possible changes should be cost-justified and incorporated into the long term strategy.

Keeping track of (and measuring) the performance of the DBMS is therefore an important part of the DBA's function. The DBA should establish and maintain records of

The DBA will also need to establish and document procedures for

It is the responsibility of the DBA to monitor the database environment on a continuing basis, in order to ensure that an efficient level of service is provided while database integrity is maintained. This responsibility for monitoring takes the form of a variety of activities and procedures, of which performance management is but one.

The Adabas Online System provides the DBA with a powerful tool for monitoring the database. See the Adabas Online Systems documentation for more information.

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