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1.1 The Evolution of Database Systems

1.1 The Evolution of Database Systems. Database: a collection of data that is managed by a DBMS The DBMS is expected to: 1) Specify the schema using a specialized data-definition language 2) Give users the ability to query and modify the data using data-manipulation language

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1.1 The Evolution of Database Systems

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  1. 1.1 The Evolution of Database Systems • Database: a collection of data that is managed by a DBMS • The DBMS is expected to: 1) Specify the schema using a specialized data-definition language 2) Give users the ability to query and modify the data using data-manipulation language 3) Support the storage of very large amounts of data 4) Enable durability 5) Control access to data from many users at once (isolation and atomicity) Database Systems

  2. 1.1.1 Early Database Management Systems • The first commercial DBMS appeared in the late 1960’s. • File systems : only item (3) supported • Applications of DBMS: • 1) Banking systems • 2) Airline reservation systems • 3) Corporate record keeping • Hierarchical model and network model Database Systems

  3. 1.1.2 Relational Database Systems • Since 1970, data systems change significantly. • Relations • SQL • Object-oriented features Database Systems

  4. 1.1.3 Smaller and Smaller Systems • Database systems available for even very small machines. • The use of documents often tagged using XML Database Systems

  5. 1.1.4 Bigger and Bigger Systems • Some important examples: • 1) Google • 2) Satellites • 3) Flickr or Amazon • 4) YouTube • 5) Peer-to-peer file-sharing systems Database Systems

  6. 1.1.5 Information Integration • To build structures on top of existing databases • 1) Data ware-houses • 2) Middleware: an integrated model Database Systems

  7. 1.2 Overview of a Database Management System • (See Fig. 1.1) • Two distinct sources of commands: 1) Conventional users and application programs 2) A database administrator Database Systems

  8. 1.2 Overview of a Database Management System Database Systems

  9. 1.2.1 Data-Definition Language Commands • Metadata Database Systems

  10. 1.2.2 Overview of Query Processing • Two separate subsystems: • 1) Answering the query • a. Buffer manager • b. Storage manager • 2) Transaction processing • a. A concurrency-control manager, or scheduler, • responsible for assuring atomicity and isolation • of transactions • b. A logging and recovery manager, responsible • for the durability of transactions Database Systems

  11. 1.2.3 Storage and Buffer Managementms • The kinds of information: • 1) Data • 2) Metadata • 3) Log records • 4) Statistics • 5) Indexes Database Systems

  12. 1.2.4 Transaction Processing • It is normal to group one or more database operations into a transaction, which is a unit of work. • The tasks performed by the transaction processor: • 1) Logging • 2) Concurrency control • 3) Deadlock resolution Database Systems

  13. 1.2.5 The Query processor • Two components: • 1) Query compiler ⇒ query plan • a. Query parser • b. Query preprocessor • c. Query optimizer • 2) Execution engine Database Systems

  14. 1.3 Outline of Database-System Studies • Five parts: • Relational database modeling • a. Functional dependencies and normalization • b. E/R model, UML, and ODL • 2) Relational database programming • a. Relational algebra, Datalog • b. SQL • 3) Semistructured data modeling and programming • a. XML, DTD, and XML schema • b. XPATH, XQuery, XSLT Database Systems

  15. 1.3 Outline of Database-System Studies • 4) Database system implementation • a. Storage management • b. Query processing • c. Transaction processing • 5) Modern database system issues • a. Search engines • b. Information integration • c. Data mining • d. Data-stream systems • e. Peer-to-peer systems Database Systems

  16. The End. Database Systems

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