Implementing the database design involves:
Implementing DB2 objects
Loading data
Managing data
Altering the design as necessary
After using a relational database for a while, we might want to change some aspects of its design.
To alter the database design we need to change the definitions of DB2 objects.
The following list will give some of the differences between DB2 and VSAM.
| Feature | DB2 | VSAM |
|---|---|---|
| Hardware Independence | PC to mainframe | Only Mainframe |
| OS Independence | NT, Unix and OS/390 | Only OS/390 |
| Ease of development | Standard SQL Stored procedure & triggers |
Not so simple No such option |
| Ease of maintenance | Standard SQL | Difficult |
| Security | High degrees of security | Only at Dataset level |
| Referential Integrity | DB2 enforces it | Developers responsibility |
| Query Interface | Easy to view/modify | Not available |
| Performance | Better for even large data Optimizer handles |
Better when data is less Developer responsible |
| Performance Tuning | Can be tuned anytime Can be at SQL level Tools available for aiding Abundant tuning skills |
Depends on initial design Only application level No tuning aids Tuning skills are rare |
| Reorganization | Direct reorganization Online reorg possible |
Delete & recreate Downtime needed |
| Recovery | Managed by DB2 Always recoverable From log / backup Auto Recovery |
Managed by CICS/IMS No recovery in batch From backup only Manual Restore |
| Backup | Online backup possible Incremental backup |
Downtime needed No incremental backup |
| Disaster Recovery | Supported by DB2 | Part of DASD recovery |
| Data Archival | Selective archival Selective retrieval Up to row level archival |
No Selective archival No Selective retrieval Dataset level archival |
| Data types | Images, Video, Audio, and so on. Contents can be in file |
Text only No such option |
If you have any doubts or queries related to this chapter, get them clarified from our Mainframe experts on ibmmainframer Community!