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Don Burleson Blog 







Oracle vs. DB2 UDB

Oracle Database Tips by Donald BurlesonApril 20,  2015

Every database vendor desires that their database be ANSI compliant, an absolute requirement for today's business applications.  However, being ANSI compliant is only a small part of the picture.

When DB2 ruled the mainframe world, IBM sought to make OS390 DB2 more readily available for platforms outside MVS/ESA.  In 1996, IBM announced a totally new product, DB2 UDB (their Universal database), a DB2-like DBMS which ran on a multitude of UNIX and Linux platforms.

Later in the 1990's, Oracle followed suit, calling their Oracle 8 database engine the Oracle Universal Server (OUS).

Both UDB and Oracle believe that their offerings are superior, and both offer migration packages.  Oracle offers the Oracle Migration Workbench.

While both DB2 UDB and Oracle are 100% ANSI compliant, there are still important "extensions" to their respective databases, subtle change that make their products special and different.  These areas of competition include:

  • Database Security - While IBM mainframe DB2 has a decades-long head start on the mainframe, UDB and Oracle are in a head to head competition for implementing a vast array of security features.
  • Development platforms - Oracle offers the integrated APEX development platform and SQL*Forms.
  • Procedural language features - Oracle has the Procedural language SQL (PL/SQL) vs. DB2 UDB with their SQL Procedural language (SQL/PL).
  • High availability - Both UDB and Oracle offer a host of HA features for continuous availability.  Oracle offers RAC clusters for shared database, plus replication solution vs. Oracle Streams, Oracle Data Guard and Oracle advanced multi-master replication.
  • Performance - Database performance is critical, but it's very difficult to gat an apples-to-apples comparison of UNIX vendor database products.  Areas include parallelism.
  • SQL Optimizer - Both IBM and Oracle have invested zillions of dollars in a SQL optimizer strategy that always chooses the "best" execution plan for SQL.
  • SQL language extensions - While both UDB and Oracle have ANSI standard SQL, vendors have a strong incentive to add "extensions", such as Oracle with their unique DECODE operator.
  • Self-management features - Both UDB and Oracle are struggling to incorporate automated features to make database administration easier and more automated.  For Oracle we see automated storage management (ASM), automated memory management (AMM), and automated database diagnostic management (ADDM). 
  • Backup & Recovery - a critical area of database management, both UDB and Oracle offer backup and recovery features.  Within Oracle's Recovery Manager (RMAN), we see block-level backups and hot backups.
  • Database Administration tools - Both UDB DB2 and Oracle offer different DBA management tools.  Areas include partitoning.

Now let's look at specific differences between UDB and Oracle syntax.

UDB vs. Oracle SQL syntax differences

  • Oracle provides the built-in pseudo column level when using CONNECT BY PRIOR
  • DB2 offers the DB2 Node type SQL, which is a DB2 extension currently available on developerWorks DB2.


References on UDB vs. Oracle




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