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DB2 - Implementing And Altering Database Design

Implementing the database design involves:

  1. Implementing DB2 objects

  2. Loading data

  3. Managing data

  4. Altering the design as necessary

Altering Database Design:

  1. After using a relational database for a while, we might want to change some aspects of its design.

  2. To alter the database design we need to change the definitions of DB2 objects.

Advantage of DB2 over VSAM (or) Difference between DB2 and VSAM:

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

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