It is hard to imagine that there are still applications that have nothing to do with the database now. Even Microsoft's next-generation operating system, Vista, needs to use its database to organize its new file system. It can be said that after years of development, data has become the most valuable resource for the entire informatization process and the next stage of development, and the technological development and progress of databases that preserve and manage data resources have become the most worthy of concern and attention. From hierarchical databases to managing relational databases, and even the current hybrid database DB2 9 that supports both relational and XML, database management technology has roughly gone through the above three stages in its nearly 40 years of development.
IMS: Early Hierarchical Database
Data management before the emergence of database management systems was very primitive and simple. When data processing relied on perforated cards, data management at that time was just physical storage and processing of cards. Data storage and management are extremely troublesome and complex, and cannot reflect efficiency at all. After IBM produced its first disk drive (Model 305 RAMAC) in 1956, it triggered a revolution in data management and thus allowed data to be stored randomly. Since then, the earliest version of the database, namely the Mesh Database Management System (DBMS), appeared, which was successfully developed by General Electric in 1961. Its IDS (Integrated DataStore) is the world's first mesh DBMS and the first DBMS. However, it can only run on the General Electric host, and the database has only one file, and all tables must be generated by manual encoding, which has great limitations. To this end, the hierarchical database IMS (Information Management System) developed by IBM has been greatly welcomed and has become the most famous and typical hierarchical database management system.
In 1966, IBM worked with its clients (Lockville, North America and Caterpillar) to develop a new database to help NASA manage the tedious data in the grand Apollo program, and in 1968 it was completed by IBM engineers. In 1969, the database was renamed "IMS" when it was released as IBM's product. In 1969, NASA successfully launched Apollo 11 to achieve its first landing in the moon, NASA continued to use the product in its space shuttle program. Until today, the database has been in use, finding a new role in today's Internet application connectivity, business intelligence and other applications.
RDBMS: The emergence of relational databases
Although hierarchical databases can already solve the problems of data concentration and sharing well, they still lack data independence and abstraction levels. Fortunately, in 1970, IBM researchers proposed the concept of relationship model, thus laying the theoretical foundation for relationship model. His paper, "A Relational Model of Data for Large Shared Data Banks", is also considered an epoch-making milestone in the history of database systems. After continuous development and demonstration, the more advantageous relational databases have finally become the mainstream of the market. Subsequently, in 1974, IBM's Ray Boyce and Don Chamberlin proposed the SQL language, which implemented all operations in the database life cycle, setting another milestone for relational databases.
In 1979, IBM completed the first DBMS to implement SQL. In the early 1980s, IBM used the second phase of RDBMS and SQL to create a new database product and named it DB2, a database product with the second generation of technology. And over the past years, DB2 has evolved from an important mainframe product to a product that can run on various server platforms. Especially in System 390 (now known as System z), DB2 has become the core of distributed computing.
Despite the continuous competition among manufacturers' database products in the same period, DB2 has received widespread application and praise in the high-end enterprise application market. After years of development and progress, there are nearly 500,000 DB2 data servers running on System z and Intel platform with Linux systems installed.
IBM DB2 9: The first hybrid data server
With the development of the informatization process and the need for information exchange between enterprises and within enterprises, XML, as a standardized data storage format, is facing huge growth in its data volume. In fact, every industry is implementing XML data standards, and the new version of Microsoft Office software will also store documents in XML format. In addition, more and more companies are turning to XML technology to exchange data between different systems and applications and adapt to rapidly changing environments, thus helping them achieve SOA step by step. DB2 9 (codenamed Viper), which combines the characteristics of relational and hierarchical databases, introduces another possibility - a hybrid database, which can support XML data very well, and also supports other technologies including SQL, tabular data structures and various DBMS features.
Until then, file systems could handle simple tasks, but they did not perform well when they needed to process a large amount of documents. Concurrency, recovery, security, and availability issues become difficult to manage. Although the Commercial Relational Database Management System (DBMS) solves these problems, it is lacking in other ways. DBMS usually just provides two basic database design options - storing each XML document intact as a large object, or "ripping" it apart and scattering it in multiple columns of multiple tables. This not only cannot fully reflect the XML hierarchy, but also is inefficient and not flexible enough.
In addition, pure XML DBMS introduces a new type of environment into IT infrastructure, but such an environment has not yet been tested, and its integration capabilities, required personnel skills, and future vitality are also uncertain. Therefore, it is necessary to find systems that can efficiently share, search and manage large amounts of company XML documents and messages to help enterprises reduce the time and work required to store and use XML data, in order to reduce application development costs and improve business flexibility. The hybrid database DB2 9 just meets this need. Through DB2 9, users can use the same database object to manage "traditional" SQL data and XML documents at the same time, and even write a query to search and process these two forms of data at the same time.
DB2, which has such characteristics, is the first and only database in the industry that can use industry-standard interface relational data to manage pureXML. It has unique innovations in three fields: XML data management, data compression and SAP optimization. Among them, the most important function is XML data management, which uses IBM's "pureXML" solution to manage data stored in XML format.
This means that DB2 9 can provide "original" storage of XML data without converting the data into row and column formats, and without storing it as a large object. To implement such a function, IBM has extended DB2 to include the following new technologies:
New storage technology，Can be managed efficiently XML Hierarchy inherent in documents。
New indexing technology，Can be improved in XML Speed of searching between and within documents。
New query language support（for XQuery）、
New graphical query builder（for XQuery）and new query optimization techniques。
Verification based on user-provided mode XML Data capability。
New management features，Includes extensions to key database tools。
Interface with popular application programming（API）Integration。
By applying compression technology, DB2 9 can save customers 40-80% of storage needs in actual testing, while maintaining and even improving application performance. Based on the revolutionary innovation and performance of DB2 9, SAP also chose DB2 9 as a data server for small and medium-sized customers using mySAP commercial applications.