File management overview
File management tasks
You might want to designate one or more persons at your site to be responsible for all tasks related to file management. File management tasks include creating, maintaining, and administering Model 204 database files, and organizing the files for maximum efficiency in data retrieval.
The users performing file management tasks (thus acting in the role of "file manager,") must be proficient in both the same kind of tasks that are required for all database management systems (such as as data allocation, storage, and retrieval, and transaction backout) but also those unique to Model 204. It is also to be expected that a good file manager understands application design, and SOUL coding techniques to assist the application developers in their tasks.
File manager privileges are established at the file level: privileges for each file are defined on the password used to open the file or the PRIVDEF (default) file privileges when no password is supplied on the file open.
The file manager works closely with the system manager. System manager duties include starting, stopping, and monitoring the Model 204 system, and setting user priorities and security.
Dictionary/204 File Management Subsystem facility
If you use the Model 204 data administration product, Dictionary/204, you have access to the File Management Subsystem facility (FILEMGMT). You can choose to create and maintain Model 204 files using FILEMGMT instead of entering commands in a file or on the command line.
FILEMGMT is a full-screen interface that prompts you for the specific file definition information it needs to automatically construct the Model 204 commands that create and define the file. FILEMGMT provides automatic file sizing and other time-saving features.
FILEMGMT also stores the entries in your site's Dictionary for the files, fields, records, and field groups that you create. For more information on the Dictionary, refer to the Rocket Model 204 Dictionary/204 and Data Administration Guide.
In addition to creating new files and providing automatic file sizing, FILEMGMT can be used to add fields or records to existing files, to change file parameters or file size, and to view or copy file information. FILEMGMT tasks are described throughout this manual.
Even if you intend on using the FILEMGMT APSY, the File Manager should have a solid knowledge of the rules and techniques involved in the creation and maintenance of Model 204
Getting started
You can perform most file management tasks in two ways:
- Manually, by creating procedures containing commands or directly on the command line
- Using the File Management Subsystem Facility (FILEMGMT)
This guide describes both ways of performing the tasks.
The following tables describe where to find information about file creation and file management tasks.
Where applicable, the Order column indicates the order in which you should perform the tasks.
| Order | Task | For information, see ... |
|---|---|---|
| 1 | Understanding Model 204 file architecture and file managment |
File Architecture Overview and the contents of this page, respectively |
| 2 | Designing your files for most efficient storage and best performance; determining size and security requirements | File Design |
| 3 | Designing your Model 204 data structures for effective and efficient processing | Repeating Field Group Design and Field Design (File Management)|Field Design]] |
|
4 (if you create the file manually) |
Calculating file size: Calculating size for Table A, Table B, Table X, Table C, Table D, Table E Allocating disk space and data sets Note: These calculations are done for you if you create files using FILEMGMT, which is the recommended method. But the information is useful to know in any case. |
File Size Calculation |
| 5 |
Creating files:
|
|
| 6 | Initializing files | Initializing Files Manually |
| Task | For information, see ... | |
|---|---|---|
|
Loading data into a file; Load raw data from a sequential data set into records in a Model 204 file. |
||
| Managing deferred updates | Deferred Update Feature | |
| Managing the size of file tables; options and parameters for automatic or manual increases | Overview | |
| Safeguarding file integrity and recovering files; backing out transactions; running media recovery | File Integrity and Recovery ; Transaction Back Out ; Media Recovery | |
| Dumping and restoring files: creating a backup copy of your data; moving files; adjusting internal space calculation | File Dumping and Restoring | |
| Managing Model 204 security for logins, files, and records; defining passwords and file privileges | Security | |
| Monitoring file use on the system and system performance; compiling file statistics | File Statistics and Tuning | |
| Reorganizing files | File Reorganization | |
| Displaying a field, file, or record; Broadcasting a file message | Overview |