DB2 is one of IBM’s lines of relational database management system (or, as IBM now calls it, data server) software products within IBM’s broader Information Management Software line.
Although there are different “editions” and “versions” of DB2 which run on devices ranging from handhelds to mainframes, most often DB2 refers to DB2 Enterprise Server Edition or the top-of-the-line DB2 Data Warehouse Edition (DB2 DWE), which runs on Unix, Windows or Linux servers; or DB2 for z/OS. Beside DB2 there exists Informix, which was acquired by IBM in 2001.
DB2 is available in several “editions,” or licensing arrangements. By opting for a reduced-feature “edition,” IBM allows customers to avoid paying for database features which they do not need. Sample editions include the Express, Workgroup, and Enterprise Edition.
The most sophisticated edition for Linux/UNIX/Windows is DB2 Data Warehouse Enterprise Edition, or DB2 DWE for short. This edition is intended for mixed workload (OLTP and data warehousing) or business intelligence (BI) implementations. DB2 DWE includes several “BI” features such as ETL, data mining, OLAP acceleration, and in-line analytics.
DB2 for z/OS is available under its own licensing terms. Starting with Version 8, IBM brought DB2 for z/OS and for the other platforms into much closer alignment. (Previously there were significant differences in SQL vocabularies, for example.)
DB2 for z/OS has some exclusives notably Multi-Level Security (MLS), extremely large table sizes, and hardware-assisted compression owing to its special environment and the demanding needs of its customers. DB2 for z/OS has always been known for its leading OLTP performance and capabilities, and for its reliability and availability to support mission-critical business operations, but the z/OS version is now starting to acquire BI features as well, such as materialized query tables (MQTs) and star schema. Oracle’s CEO Larry Ellison commented that DB2 for z/OS is the one competitive database he respects and admires.
On January 30, 2006, IBM released a no-charge version of DB2 called DB2 Express-C. This was an expected response to the recently announced free versions of Oracle 10g and Microsoft SQL Server. Unlike Microsoft or Oracle’s free editions, Express-C has no limit on number of users or on database size.
While versions 8.2 and 9.1 of DB2 Express-C imposed hardware limits on the server on which it ran, DB2 Express-C 9.5 can run on Windows and Linux machines of any size, but the database engine will not utilize more than two CPU cores and 2GB RAM. In 2007, IBM introduced a yearly support subscription called the Fixed Term License (FTL), which offers a year of telephone support for Express-C for US$3000 per server.
Purchasing the FTL also allows the DB2 Express-C engine to use up to four CPU cores and 4GB RAM. Users of DB2 Express-C who don’t purchase an FTL subscription can receive support and assistance on a free, public web forum staffed by IBM technicians and other DB2 users.
Historically, prime position in the database management software market has been held by Oracle. On May 3, 2004, IBM’s head of database development and sales, Janet Perna, claimed their main competitors were Oracle in the context of advanced transaction handling and Teradata in the context of decision support systems (e.g. data warehousing).
However, there are competitors in smaller markets, including Microsoft SQL Server (which is only available for Microsoft Windows), open source products such as FirebirdSQL, PostgreSQL and MySQL, and niche players such as Sybase and MaxDB.
In the clustered DBMS arena, where databases can grow to many terabytes, IBM’s Database Partitioning Feature (DPF) is often pitted against Oracle Real Application Clusters (RAC), a shared-disk implementation formerly known as Oracle Parallel Server (OPS).
DB2 for z/OS arguably has fewer direct competitors, but Oracle is attracting customers to its Linux on zSeries products, although apparently not at the expense of DB2. CA-Datacom and Software AG’s ADABAS are competing relational databases for z/OS, and there are certain niche products as well (Model 204, SUPRA SQL, NOMAD, etc.)
Oracle has a 31-bit RDBMS available for z/OS. Non-relational databases that “compete” include IMS, and CA-IDMS, among others.
IBM and DB2 are frequently at or near the top of the TPC-C and TPC-H industry benchmarks published on the Transaction Processing Performance Council’s website.
In 2006 IBM stepped up its competition in the emerging data warehouse appliance market by releasing a product line of pre-configured hardware/software systems combining DB2 Data Warehouse Edition with either IBM system p (AIX) or IBM system x (Linux) servers.
This family of “warehouse appliance-like” systems was given the name IBM Balanced Configuration Unit, or BCU, and is aimed at the warehouse appliance market typified by Netezza and DATAllegro, but it differentiates itself in that it uses the full-featured version of DB2 instead of a single-purpose warehouse-oriented RDBMS.