Monday, 11 August 2008

25 years of DB2

What kind of a mainframe blog doesn’t mention DB2’s 25th birthday? I hang my head in shame. DB2 celebrated its birthday on the 7th July this year, and like a forgetful relative, I don’t send a card until a month later. But, finally, here is my take on 25 years of DB2.

DB2 – which stands for DataBase 2 – first saw the light of day as an MVS application in 1983. It is a relational database and uses SQL (Structured Query Language) – pronounced SQL by mainframers and "sequel" by non-mainframers, apparently. Where did it come from? In the 1970s, Ted Codd created a series of rules for relational databases, which DB2 was very loosely based on. However, originally, DB2 did break many of Codd’s rules. There was also a VM product called SQL/DS, which was similar in nature.

As well as MVS (or z/OS as it’s called in its current incarnation), DB2 is available on other platforms. During the 1990s versions were produced for OS/2 (if you remember that one) Linux, Unix, and Windows. There have been a variety of naming conventions over the years. Things like DB2/VSE and DB2/6000, which were replaced by DB2 for VSE and then DB2 UDB (Universal DataBase). This current naming convention can make it harder to work out whether a mainframe version of DB2 or a server version of DB2 is being discussed in any article on the topic.

Interestingly, although mainframe and server versions of DB2 are currently very similar in functionality, they are written in different languages. The mainframe version is written in PL/S and the server version in C++.

In the early days, the big competition was Oracle and Informix. Well, IBM bought Informix in 2001, and happily runs Oracle on a zLinux partition. There is also a 31-bit version of Oracle available for z/OS.

Of course, DB2 isn’t IBM’s only database. It has its relational IMS DB. People interested in IMS DB will be interested in the Virtual IMS Connections user group at

As they say, other mainframe databases are available, including: CA-Datacom, CA-IDMS, Cincom’s SUPRA, Computer Corporation of America’s Model 204, Select Business Solutions’ NOMAD, and Software AG’s Adabas.

DB2 is currently at Version 9, which you might remember was code-named Viper before its launch.

Happy belated birthday DB2.

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