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Monday, April 27, 2009

Why DB2 and why not VSAM (DB2 Vs VSAM)?

Why DB2 and why not VSAM (DB2 Vs VSAM)?



This is the common query raised by the programmers, whether to go with DB2/VSAM, hope below information helps.


VSAM

DB2

Definition

Database with file Concepts

Database built on File management storage system-DBMS concepts




Security levels

Provides at Dataset level only

Provides Good security levels at various levels (like table, table space etc.,)




Data Maintenance

It’s difficult compared to DB2.

Data retrieval or insertion or updates etc, is a bit difficult (puts more burden on programmer to achieve this).

Simply speaking Query interface is not supported

It’s easy to maintain data by using SQL

Data retrieval or insertion or updates etc, is far easier using SQl .

Query interface is supported




Referential Integrity

Again it programmers responsibility to design it accordingly

It’s one of the feature of DB2




Recovery

Recoverable only from Backup file

Auto recovery is not possible

Recoverable from DB2 log/ Backup

Auto recovery is possible




Backup

Incremental backup is not supported.

Incremental backup is supported




Performance

Performance is better than DB2, when small amount of data is used by the transaction

DB2 has good performance over VSAM, when high volume of data is used by the transactions




Accessible

Mainframes only

Can be shared with Distributed systems

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