Q. With the help of a suitable diagram gives module wise explanation of system architecture of DBMS.
Sol. A Database management is a collection of interrelated data and collection of programs to access that data, the data describes one particular enterprise. Database systems are ubiquitous today, and most people interact either directly or indirectly, with databases many times everyday. A major purpose of the database system is to provide users with an abstract view of the data. That is the system hides certain details of how the data are stored and maintained. Underlying the structure of a database is the data model: a collection of conceptual tools for describing data, data relationships, data is a widely used data model and it provides a convenient graphical representation to view data, relationships and constraints.
Database System Structure: A database system is partitioned into modules that deal with each of the responsibilities of the overall system. The functional components of a database system can be broadly divided into the storage manager and the query processer components. The storage manager is important because database typically require a large amount of storage space. Separate databases range is size from hundreds of gigabytes to, for the largest database terabytes of data. A gigabyte is 1000 mega bytes (1 billion bytes) and a terabyte is 1 million mega bytes (1 trillion bytes). Since main memory of computer cannot store this much information is stored on disks. Data is moved between disk storage and main memory as needed. Since the movement of data to and from disk is slow relative to the speed of the central processing unit, it is imperative that the database system structures the data so as to minimize the need to move data between disk and main memory. The query processor is important because it helps the database system simplify and facilitate access to data. High level views helps to achieve this goal; with them, users of the system are not be bounding unnecessarily with the physical details for the implementation of the database system to translate updates and queries written in a non procedural language, at the logical level, into an efficient sequence of operations at the physical level.
Components of DBMS Environment: Database management system environment's main components are as: (i) Database users and Database Administrator. (ii) Transaction Management. (iii) The query processor. (iv) Storage Manager. (v) Disk Storage. (i) Database Users: Database users can be categorized into several classes, and each class of users usually uses a different type of interface to the database. Different users are as: (A) Naïve users. (B) Application programmer. (C) Sophisticated users. (D) Specialized users. Database Administrator: One of the main reasons for using DBMS is t have central control of both the data and the programs that access those data. A person who has such central control over the system is called and Database Administrator. The functions of DBA includes: (A)Schema definition. (B)Storage structure and access method definition. (C)Schema and physical organization modification. (D)Granting of authorization for data access. (E)Routine maintenance. (ii) Transaction Management: The transaction management subsystem is responsible for ensuring that the database remains in a consistent state despite system failures. The transaction manager also ensures that concurrent transaction execution proceed without conflicting. (iii) The Query Processor: The query processor subsystem compels and executes DDL and DML statements. The query processor components include. (A) DDL interpreter. (B) DML compiler. (C) Query evaluating engine. (iv) Storage Manager: The storage manager subsystem provides the interface between the low level data stored in the database and the application programs and queries submitted to the system. The storage manager components in clues: Authorization and integrity manager. Transaction manager. File manager. Buffer manager. (v) Disk Storage: The storage implements several data structures as part of the physical system implementation. Date files. Data dictionary. Indices.