DBMS System Instance

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A DBMS System Instance is a running software instance of a DBMS software.




  • http://en.wikipedia.org/wiki/Database
    • QUOTE: … A general-purpose DBMS is typically a complex software system that meets many usage requirements, and the databases that it maintains are often large and complex. The utilization of databases is now spread to such a wide degree that virtually every technology and product relies on databases and DBMSs for its development and commercialization, or even may have such embedded in it. Also, organizations and companies, from small to large, heavily depend on databases for their operations.

      The term database is correctly applied to the data and their containing data structures, and not to the DBMS which is a software system used to manage the database. The structure of a database is generally too complex to be handled without its DBMS, and any attempt to do otherwise is very likely to result in database corruption. DBMSs are packaged as computer software products: Well known and highly utilized DBMSs include the proprietary (ranked by highest sales[citation needed]) Oracle, Microsoft SQL Server, IBM DB2, and the open source DBMSs MySQL and PostgreSQL. Each such DBMS product currently supports many thousands of databases all over the world; the open source embedded DBMS SQLite supports many millions of copies (see Adoption there). A database is not generally portable across different DBMS, but different DBMSs can inter-operate to some degree (while each DBMS type controls a database of its own database type) by using standards like SQL and ODBC to support together a single application. A successful general-purpose DBMS is designed in such a way that it can satisfy as many different applications and application designers and builders as possible. A DBMS also needs to provide effective run-time execution to properly support (e.g., in terms of performance, availability, and security) as many end-users (the database's application users) as needed. Sometimes the combination of a database and its respective DBMS is referred to as a Database system (DBS).

      The design, construction, and maintenance of a complex database requires specialist skills: the staff performing these functions are referred to as database application programmers (different from the DBMS developers/programmers) and database administrators. Their tasks are supported by tools provided either as part of the DBMS or as free-standing (stand-alone) software products. These tools include specialized database languages including data definition languages (DDLs), data manipulation languages (DMLs), and query languages. These can be seen as special-purpose programming languages, tailored specifically to manipulate databases; sometimes they are provided as extensions of existing programming languages, with added special database commands. Database languages are generally specific to one data model, and in many cases they are specific to one DBMS type. The most widely supported standard database language is SQL, which has been developed for the relational data model and combines the roles of DDL, DML, and a query language.

      A way to classify databases involves the type of their contents, for example: bibliographic, document-text, statistical, multimedia objects, etc. Another way is by their application area, for example: Accounting, Music compositions, Movies, Banking, Manufacturing, Insurance, etc. Wikipedia relies on a database of encyclopedic articles and related information.