IBM DB2 contains database server products developed by IBM. These products all support the relational model, but in recent years some products have been extended to support object-relational features and non-relational structures like JSON and XML.
Historically and unlike other database vendors, IBM produced a platform-specific DB2 product for each of its major operating systems. However, in the 1990s IBM changed track and produced a DB2 common product, designed with a common code base to run on different platforms.
Maps, Directions, and Place Reviews
Current supported platforms
- DB2 for Linux, UNIX and Windows (informally known as DB2 LUW)
- DB2 for z/OS (mainframe)
- DB2 for i (formerly OS/400).
- DB2 for VSE & VM
Db2 Connect Video
History
DB2 traces its roots back to the beginning of the 1970s when Edgar F. Codd, a researcher working for IBM, described the theory of relational databases and in June 1970 published the model for data manipulation.
In 1974 the IBM San Jose Research center developed a relational DBMS, System R, to implement Codd's concepts. A key development of the System R project was SQL. To apply the relational model Codd needed a relational database language he named DSL/Alpha. At the time IBM didn't believe in the potential of Codd's ideas, leaving the implementation to a group of programmers not under Codd's supervision, who violated several fundamentals of Codd's relational model; the result was Structured English QUEry Language or SEQUEL. When IBM released its first relational database product, they wanted to have a commercial-quality sublanguage as well, so it overhauled SEQUEL and renamed the basically new language Structured Query Language (SQL) to differentiate it from SEQUEL. The acronym SEQUEL was changed to SQL because "SEQUEL" was a trademark of the UK-based Hawker Siddeley aircraft company.
IBM bought Metaphor Computer Systems to utilize their GUI interface and encapsulating SQL platform that had already been in use since the mid 80's. In parallel with the development of SQL IBM also developed Query by Example (QBE), the first graphical query language.
IBM's first commercial relational database product, SQL/DS, was released for the DOS/VSE and VM/CMS operating systems in 1981. In 1976 IBM released Query by Example for the VM platform where the table-oriented front-end produced a linear-syntax language that drove transactions to its relational database. Later the QMF feature of DB2 produced real SQL and brought the same "QBE" look and feel to DB2.
The name DB2, or IBM Database 2, was first given to the Database Management System or DBMS in 1983 when IBM released DB2 on its MVS mainframe platform.
When Informix Corporation acquired Illustra and made their database engine an object-SQL DBMS by introducing their Universal Server, both Oracle and IBM followed suit by changing their database engines to be capable of object-relational extensions. In 2001, IBM bought Informix Software and in the following years incorporated Informix technology into the DB2 product suite. DB2 can technically be considered to be an object-SQL DBMS.
For some years DB2, as a full-function DBMS, was exclusively available on IBM mainframes. Later IBM brought DB2 to other platforms, including OS/2, UNIX and MS Windows servers, then Linux (including Linux on z Systems) and PDAs. This process occurred through the 1990s. The inspiration for the mainframe version of DB2's architecture came in part from IBM IMS, a hierarchical database, and its dedicated database manipulation language, IBM DL/I. DB2 is also embedded in the i5/OS operating system for IBM System i (iSeries, formerly the AS/400), and versions are available for z/VSE and z/VM. An earlier version of the code that would become DB2 LUW (Linux, Unix, Windows) was part of an Extended Edition component of OS/2 called Database Manager.
IBM extended the functionality of Database Manager a number of times, including the addition of distributed database functionality by means of Distributed Relational Database Architecture (DRDA) that allowed shared access to a database in a remote location on a LAN. (Note that DRDA is based on objects and protocols defined by Distributed Data Management Architecture (DDM).)
Eventually IBM took the decision to completely rewrite the software. The new version of Database Manager was called DB2/2 and DB2/6000 respectively. Other versions of DB2, with different code bases, followed the same '/' naming convention and became DB2/400 (for the AS/400), DB2/VSE (for the DOS/VSE environment) and DB2/VM (for the VM operating system). IBM lawyers stopped this handy naming convention from being used and decided that all products needed to be called "product FOR platform" (for example, DB2 for OS/390). The next iteration of the mainframe and the server-based products were named DB2 Universal Database (or DB2 UDB).
In the mid-1990s, IBM released a clustered DB2 implementation called DB2 Parallel Edition, which initially ran on AIX. This edition allowed scalability by providing a shared nothing architecture, in which a single large database is partitioned across multiple DB2 servers that communicate over a high-speed interconnect. This DB2 edition was eventually ported to all Linux, UNIX, and Windows (LUW) platforms and was renamed to DB2 Extended Enterprise Edition (EEE). IBM now refers to this product as the Database Partitioning Feature (DPF) and sells it as an add-on to their flagship DB2 Enterprise product.
In mid 2006, IBM announced "Viper," which is the codename for DB2 9 on both distributed platforms and z/OS. DB2 9 for z/OS was announced in early 2007. IBM claimed that the new DB2 was the first relational database to store XML "natively". Other enhancements include OLTP-related improvements for distributed platforms, business intelligence/data warehousing-related improvements for z/OS, more self-tuning and self-managing features, additional 64-bit exploitation (especially for virtual storage on z/OS), stored procedure performance enhancements for z/OS, and continued convergence of the SQL vocabularies between z/OS and distributed platforms.
In October 2007, IBM announced "Viper 2," which is the codename for DB2 9.5 on the distributed platforms. There were three key themes for the release, Simplified Management, Business Critical Reliability and Agile XML development.
In June 2009, IBM announced "Cobra" (the codename for DB2 9.7 for LUW). DB2 9.7 adds data compression for database indexes, temporary tables, and large objects. DB2 9.7 also supports native XML data in hash partitioning (database partitioning), range partitioning (table partitioning), and multi-dimensional clustering. These native XML features allows users to directly work with XML in data warehouse environments. DB2 9.7 also adds several features that make it easier for Oracle Database users to work with DB2. These include support for the most commonly used SQL syntax, PL/SQL syntax, scripting syntax, and data types from Oracle Database. DB2 9.7 also enhanced its concurrency model to exhibit behavior that is familiar to users of Oracle Database and Microsoft SQL Server.
In October 2009, IBM introduced its second major release of the year when it announced DB2 pureScale. DB2 pureScale is a database cluster solution for non-mainframe platforms, suitable for Online Transaction Processing (OLTP) workloads. IBM based the design of DB2 pureScale on the Parallel Sysplex implementation of DB2 data sharing on the mainframe. DB2 pureScale provides a fault-tolerant architecture and shared-disk storage. A DB2 pureScale system can grow to 128 database servers, and provides continuous availability and automatic load balancing.
In 2009, it was announced that DB2 can be an engine in MySQL. This allows users on the System i platform to natively access the DB2 under the IBM i operating system (formerly called OS/400), and for users on other platforms to access these files through the MySQL interface. On the System i and its predecessors the AS/400 and the System/38, DB2 is tightly integrated into the operating system, and comes as part of the operating system. It provides journaling, triggers and other features.
In early 2012, IBM announced the next version of DB2, DB2 10.1 (code name Galileo) for Linux, UNIX, and Windows. DB2 10.1 contained a number of new data management capabilities including row and column access control which enables 'fine-grained' control of the database and multi-temperature data management that moves data to cost effective storage based on how"hot" or "cold" (how frequently the data is accessed) the data is. IBM also introduced 'adaptive compression' capability in DB2 10.1, a new approach to compressing data tables.
In June 2013, IBM released DB2 10.5 (code name "Kepler").
On 12 April 2016, IBM announced DB2 LUW 11.1, and in June 2016 it was released.
Editions
IBM offers seven editions: Advanced Enterprise Server Edition Advanced Workgroup Server Edition Enterprise Server Edition Workgroup Server Edition Express Edition Developer Edition and Express-C.
DB2 Express-C is free of charge version of DB2 but limited to two CPU cores and 16GB of RAM and without Enterprise support and fixpacks. DB2 Express-C has no limit on number of users or on database size.
DB2 for z/OS (the mainframe) is available in its traditional product packaging, or in the Value Unit Edition, which allows customers to instead pay a one-time charge.
DB2 also powers IBM InfoSphere Warehouse, which offers data warehouse capabilities. InfoSphere Warehouse is available for z/OS. It includes several BI features such as ETL, data mining, OLAP acceleration, and in-line analytics.
DB2 10.5 for Linux, UNIX and Windows, contains all of the functionality and tools offered in the prior generation of DB2 and InfoSphere Warehouse on Linux, UNIX and Windows.
IBM provides 2 cloud services for DB2 on its Bluemix platform:
- DB2 on Cloud: An unmanaged, hosted version of DB2.
- IBM dashDB: A managed cloud database based on the DB2 engine, with additional capabilities from the Netezza engine. Inside the dashDB family, there are 3 editions: IBM dashDB for Transactions (general purpose, transactional or web workloads), dashDB for Analytics (data warehouse), and dashDB Local (a Docker container image allowing deployment on private clouds.)
Technical information
DB2 can be administered from either the command-line or a GUI. The command-line interface requires more knowledge of the product but can be more easily scripted and automated. The GUI is a multi-platform Java client that contains a variety of wizards suitable for novice users. DB2 supports both SQL and XQuery. DB2 has native implementation of XML data storage, where XML data is stored as XML (not as relational data or CLOB data) for faster access using XQuery.
DB2 has APIs for REXX, PL/I, COBOL, RPG, FORTRAN, C++, C, Delphi, .NET CLI, Java, Python, Perl, PHP, Ruby, and many other programming languages. DB2 also supports integration into the Eclipse and Visual Studio integrated development environments.
pureQuery is IBM's data access platform focused on applications that access data. pureQuery supports both Java and .NET. pureQuery provides access to data in databases and in-memory Java objects via its tools, APIs, and runtime environment as delivered in IBM Data Studio Developer and IBM Data Studio pureQuery Runtime.
Error processing
An important feature of DB2 computer programs is error handling. The SQL communications area (SQLCA) structure was once used exclusively within a DB2 program to return error information to the application program after every SQL statement was executed. The primary, but not singularly useful, error diagnostic is held in the field SQLCODE within the SQLCA block.
The SQL return code values are:
- 0 means successful execution.
- A positive number means successful execution with one or more warnings. An example is
+100, which means no rows found. - A negative number means unsuccessful with an error. An example is
-911, which means a lock timeout (or deadlock) has occurred, triggering a rollback.
Later versions of DB2 added functionality and complexity to the execution of SQL. Multiple errors or warnings could be returned by the execution of an SQL statement; it may, for example, have initiated a Database Trigger and other SQL statements. Instead of the original SQLCA, error information should now be retrieved by successive executions of a GET DIAGNOSTICS statement.
See SQL return codes for a more comprehensive list of common SQLCODEs.
Source of the article : Wikipedia
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