What Is a Database Management System? What Is a Transaction

Collection of data central to some enterprise Overview of Databases and Essential to operation of enterprise Transaction Processing Contains the only record of enterprise activity An asset in its own right Chapter 1 Historical data can guide enterprise strategy Of interest to other enterprises State of database mirrors state of enterprise Database is persistent

What is a Database Management What is a Transaction? System? When an event in the real world changes the A Database Management System (DBMS) state of the enterprise, a transaction is is a program that manages a database: executed to cause the corresponding change in the database state Supports a high-level access language (e.g. With an on-line database, the event causes the SQL). transaction to be executed in real time Application describes database accesses using A transaction is an application program that language. with special properties - discussed later - to DBMS interprets statements of language to guarantee it maintains database correctness perform requested database access.

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What is a Transaction Processing Transaction Processing System System? Transaction execution is controlled by a TP

monitor s DBMS database n o i Creates the abstraction of a transaction, t c a analogous to the way an operating system s n a r creates the abstraction of a process t DBMS database TP monitor and DBMS together guarantee the special properties of transactions TP Monitor A Transaction Processing System consists of TP monitor, databases, and transactions 5 6

1 System Requirements System Requirements (con t)

High Availability: on-line => must be Long Lifetime: complex systems are not operational while enterprise is functioning easily replaced High Reliability: correctly tracks state, Must be designed so they can be easily does not lose data, controlled concurrency extended as the needs of the enterprise change High Throughput: many users => many Security: sensitive information must be transactions/sec carefully protected since system is accessible to many users Low Response Time: on-line => users are waiting Authentication, authorization, encryption 7 8

Roles in Design, Implementation, Roles in Design, Implementation and Maintenance of a TPS and Maintenance of a TPS (con t) System Analyst - specifies system using input Database Administrator - maintains from customer; provides complete description of database once system is operational: space functionality from customer s and user s point of allocation, performance optimization, view database security Database Designer - specifies structure of data that will be stored in database System Administrator - maintains Application Programmer - implements transaction processing system: monitors application programs (transactions) that access interconnection of HW and SW modules, data and support enterprise rules deals with failures and congestion

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OLAP OLTP vs. OLAP Analyzes historical data (terabytes) using complex queries On-line Transaction Processing (OLTP) Due to volume of data and complexity of Day-to-day handling of transactions that result from enterprise operation queries, OLAP often uses a data warehouse Maintains correspondence between database Data Warehouse - (offline) repository of state and enterprise state historical data generated from OLTP or On-line Analytic Processing (OLAP) other sources Analysis of information in a database for the Data Mining - use of warehouse data to purpose of making management decisions discover relationships that might influence

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2 Examples - Supermarket

OLTP Event is 3 cans of soup and 1 box of crackers bought; update database to reflect that event OLAP Last winter in all stores in northeast, how many customers bought soup and crackers together? Data Mining Are there any interesting combinations of foods that customers frequently bought together?

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