1. © 2011 Pearson Education, Inc. Publishing as Prentice Hall 1 Chapter 11: Data and Database Administration Modern Database Management 10 h Edition Jeffrey A. Hoffer, V. Ramesh, Heikki Topi

2. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 2 Objectives Define terms Define terms List functions and roles of data/database administration List functions and roles of data/database administration Describe role of data dictionaries and information repositories Describe role of data dictionaries and information repositories Compare optimistic and pessimistic concurrency control Compare optimistic and pessimistic concurrency control Describe problems and techniques for data security Describe problems and techniques for data security Understand role of databases in Sarbanes-Oxley compliance Understand role of databases in Sarbanes-Oxley compliance Describe problems and facilities for data recovery Describe problems and facilities for data recovery Describe database tuning issues and list areas where changes can be done to tune the database Describe database tuning issues and list areas where changes can be done to tune the database Describe importance and measures of data availability Describe importance and measures of data availability

3. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 3 Traditional Administration Definitions Data Administration: A high-level function that is responsible for the overall management of data resources in an organization, including maintaining corporate-wide definitions and standards Data Administration: A high-level function that is responsible for the overall management of data resources in an organization, including maintaining corporate-wide definitions and standards Database Administration: A technical function that is responsible for physical database design and for dealing with technical issues such as security enforcement, database performance, and backup and recovery Database Administration: A technical function that is responsible for physical database design and for dealing with technical issues such as security enforcement, database performance, and backup and recovery

4. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 4 Traditional Data Administration Functions Data policies, procedures, standards Data policies, procedures, standards Planning Planning Data conflict (ownership) resolution Data conflict (ownership) resolution Managing the information repository Managing the information repository Internal marketing of DA concepts Internal marketing of DA concepts

5. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 5 Traditional Database Administration Functions Analyzing and designing databases Analyzing and designing databases Selection of DBMS and software tools Selection of DBMS and software tools Installing/upgrading DBMS Installing/upgrading DBMS Tuning database performance Tuning database performance Improving query processing performance Improving query processing performance Managing data security, privacy, and integrity Managing data security, privacy, and integrity Data backup and recovery Data backup and recovery

6. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 6 Data Warehouse Administration New role, coming with the growth in data warehouses New role, coming with the growth in data warehouses Similar to DA/DBA roles Similar to DA/DBA roles Emphasis on integration and coordination of metadata/data across many data sources Emphasis on integration and coordination of metadata/data across many data sources Specific roles: Specific roles: Support DSS applications Support DSS applications Manage data warehouse growth Manage data warehouse growth Establish service level agreements regarding data warehouses and data marts Establish service level agreements regarding data warehouses and data marts

7. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 7 Open Source DBMSs An alternative to proprietary packages such as Oracle, Microsoft SQL Server, or Microsoft Access An alternative to proprietary packages such as Oracle, Microsoft SQL Server, or Microsoft Access mySQL is an example of an open-source DBMS mySQL is an example of an open-source DBMS Less expensive than proprietary packages Less expensive than proprietary packages Source code available, for modification Source code available, for modification Absence of complete documentation Absence of complete documentation Ambiguous licensing concerns Ambiguous licensing concerns Not as feature-rich as proprietary DBMSs Not as feature-rich as proprietary DBMSs Vendors may not have certification programs Vendors may not have certification programs

8. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 8 Database Security Database Security: Protection of the data against accidental or intentional loss, destruction, or misuse Database Security: Protection of the data against accidental or intentional loss, destruction, or misuse Increased difficulty due to Internet access and client/server technologies Increased difficulty due to Internet access and client/server technologies

9. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 9 Figure 11-2 Possible locations of data security threats

10. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 10 Threats to Data Security Accidental losses attributable to: Accidental losses attributable to: Human error Human error Software failure Software failure Hardware failure Hardware failure Theft and fraud Theft and fraud Loss of privacy or confidentiality Loss of privacy or confidentiality Loss of privacy (personal data) Loss of privacy (personal data) Loss of confidentiality (corporate data) Loss of confidentiality (corporate data) Loss of data integrity Loss of data integrity Loss of availability (through, e.g. sabotage) Loss of availability (through, e.g. sabotage)

11. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 11 Figure 11-3 Establishing Internet Security

12. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 12 Web Security Static HTML files are easy to secure Static HTML files are easy to secure Standard database access controls Standard database access controls Place Web files in protected directories on server Place Web files in protected directories on server Dynamic pages are harder Dynamic pages are harder User authentication User authentication Session security Session security SSL for encryption SSL for encryption Restrict number of users and open ports Restrict number of users and open ports Remove unnecessary programs Remove unnecessary programs

13. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 13 W3C Web Privacy Standard Platform for Privacy Protection (P3P) Platform for Privacy Protection (P3P) Addresses the following: Addresses the following: Who collects data Who collects data What data is collected and for what purpose What data is collected and for what purpose Who is data shared with Who is data shared with Can users control access to their data Can users control access to their data How are disputes resolved How are disputes resolved Policies for retaining data Policies for retaining data Where are policies kept and how can they be accessed Where are policies kept and how can they be accessed

14. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 14 Database Software Security Features Views or subschemas Views or subschemas Integrity controls Integrity controls Authorization rules Authorization rules User-defined procedures User-defined procedures Encryption Encryption Authentication schemes Authentication schemes Backup, journalizing, and checkpointing Backup, journalizing, and checkpointing

15. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 15 Views and Integrity Controls Views Views Subset of the database that is presented to one or more users Subset of the database that is presented to one or more users User can be given access privilege to view without allowing access privilege to underlying tables User can be given access privilege to view without allowing access privilege to underlying tables Integrity Controls Integrity Controls Protect data from unauthorized use Protect data from unauthorized use Domains–set allowable values Domains–set allowable values Assertions–enforce database conditions Assertions–enforce database conditions Triggers – prevent inappropriate actions, invoke special handling procedures, write to log files Triggers – prevent inappropriate actions, invoke special handling procedures, write to log files

16. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 16 Authorization Rules Controls incorporated in the data management system Controls incorporated in the data management system  Restrict:  Restrict: access to data access to data actions that people can take on data actions that people can take on data  Authorization matrix for:  Authorization matrix for: Subjects Subjects Objects Objects Actions Actions Constraints Constraints

17. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 17 Some DBMSs also provide capabilities for user- defined procedures to customize the authorization process Figure 11-5a Authorization table for subjects (salespersons) Figure 11-5b Authorization table for objects (orders) Figure 11-6 Oracle privileges Implementing authorization rules

18. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 18 Encryption – the coding or scrambling of data so that humans cannot read them Secure Sockets Layer (SSL) is a popular encryption scheme for TCP/IP connections Figure 11-7 Basic two-key encryption

19. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 19 Authentication Schemes Goal – obtain a positive identification of the user Goal – obtain a positive identification of the user Passwords: First line of defense Passwords: First line of defense Should be at least 8 characters long Should be at least 8 characters long Should combine alphabetic and numeric data Should combine alphabetic and numeric data Should not be complete words or personal information Should not be complete words or personal information Should be changed frequently Should be changed frequently

20. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 20 Authentication Schemes (cont.) Strong Authentication Strong Authentication Passwords are flawed: Passwords are flawed: Users share them with each other Users share them with each other They get written down, could be copied They get written down, could be copied Automatic logon scripts remove need to explicitly type them in Automatic logon scripts remove need to explicitly type them in Unencrypted passwords travel the Internet Unencrypted passwords travel the Internet Possible solutions: Possible solutions: Two factor–e.g. smart card plus PIN Two factor–e.g. smart card plus PIN Three factor–e.g. smart card, biometric, PIN Three factor–e.g. smart card, biometric, PIN

21. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall Sarbanes-Oxley (SOX) Requires companies to audit the access to sensitive data Requires companies to audit the access to sensitive data Designed to ensure integrity of public companies’ financial statements Designed to ensure integrity of public companies’ financial statements SOX audit involves: SOX audit involves: IT change management IT change management Logical access to data Logical access to data IT operations IT operations 21

22. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall IT Change Management The process by which changes to operational systems and databases are authorized The process by which changes to operational systems and databases are authorized For database, changes to: schema, database configuration, updates to DBMS software For database, changes to: schema, database configuration, updates to DBMS software Segregation of duties: development, test, production Segregation of duties: development, test, production 22

23. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall Logical Access to Data Personnel controls Personnel controls Hiring practices, employee monitoring, security training, separation of duties Hiring practices, employee monitoring, security training, separation of duties Physical access controls Physical access controls Swipe cards, equipment locking, check-out procedures, screen placement, laptop protection Swipe cards, equipment locking, check-out procedures, screen placement, laptop protection 23

24. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall IT Operations Policies and procedures for day-to-day management of infrastructure, applications, and databases in an organization Policies and procedures for day-to-day management of infrastructure, applications, and databases in an organization For databases: backup, recovery, availability For databases: backup, recovery, availability 24

25. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 25 Database Recovery  Mechanism for restoring a database quickly and accurately after loss or damage  Recovery facilities: Backup Facilities Backup Facilities Journalizing Facilities Journalizing Facilities Checkpoint Facility Checkpoint Facility Recovery Manager Recovery Manager

26. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 26 Back-up Facilities DBMS copy utility that produces backup copy of the entire database or subset DBMS copy utility that produces backup copy of the entire database or subset Periodic backup (e.g. nightly, weekly) Periodic backup (e.g. nightly, weekly) Cold backup–database is shut down during backup Cold backup–database is shut down during backup Hot backup–selected portion is shut down and backed up at a given time Hot backup–selected portion is shut down and backed up at a given time Backups stored in secure, off-site location Backups stored in secure, off-site location

27. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 27 Journalizing Facilities Audit trail of transactions and database updates Audit trail of transactions and database updates Transaction log–record of essential data for each transaction processed against the database Transaction log–record of essential data for each transaction processed against the database Database change log–images of updated data Database change log–images of updated data Before-image–copy before modification Before-image–copy before modification After-image–copy after modification After-image–copy after modification Produces an audit trail

28. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 28 Figure 11-8 Database audit trail From the backup and logs, databases can be restored in case of damage or loss

29. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 29 Checkpoint Facilities DBMS periodically refuses to accept new transactions DBMS periodically refuses to accept new transactions  system is in a quiet state  system is in a quiet state Database and transaction logs are synchronized Database and transaction logs are synchronized This allows recovery manager to resume processing from short period, instead of repeating entire day

30. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 30 Recovery and Restart Procedures Disk Mirroring–switch between identical copies of databases Disk Mirroring–switch between identical copies of databases Restore/Rerun–reprocess transactions against the backup Restore/Rerun–reprocess transactions against the backup Transaction Integrity–commit or abort all transaction changes Transaction Integrity–commit or abort all transaction changes Backward Recovery (Rollback)–apply before images Backward Recovery (Rollback)–apply before images Forward Recovery (Roll Forward)–apply after images (preferable to restore/rerun) Forward Recovery (Roll Forward)–apply after images (preferable to restore/rerun)

31. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 31 Transaction ACID Properties Atomic Atomic Transaction cannot be subdivided Transaction cannot be subdivided Consistent Consistent Constraints don’t change from before transaction to after transaction Constraints don’t change from before transaction to after transaction Isolated Isolated Database changes not revealed to users until after transaction has completed Database changes not revealed to users until after transaction has completed Durable Durable Database changes are permanent Database changes are permanent

32. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 32 Figure 11-9 Basic recovery techniques a) Rollback

33. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 33 Figure 11-9 Basic recovery techniques (cont.) b) Rollforward

34. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 34

35. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 35 Concurrency Control Problem–in a multi-user environment, simultaneous access to data can result in interference and data loss Problem–in a multi-user environment, simultaneous access to data can result in interference and data loss Solution–Concurrency Control Solution–Concurrency Control The process of managing simultaneous operations against a database so that data integrity is maintained and the operations do not interfere with each other in a multi- user environment The process of managing simultaneous operations against a database so that data integrity is maintained and the operations do not interfere with each other in a multi- user environment

36. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 36 Figure 11-10 Lost update (no concurrency control in effect) Simultaneous access causes updates to cancel each other A similar problem is the inconsistent read problem

37. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 37 Concurrency Control Techniques Serializability Serializability Finish one transaction before starting another Finish one transaction before starting another Locking Mechanisms Locking Mechanisms The most common way of achieving serialization The most common way of achieving serialization Data that is retrieved for the purpose of updating is locked for the updater Data that is retrieved for the purpose of updating is locked for the updater No other user can perform update until unlocked No other user can perform update until unlocked

38. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 38 Figure 11-11: Updates with locking (concurrency control) This prevents the lost update problem

39. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 39 Locking Mechanisms Locking level: Locking level: Database–used during database updates Database–used during database updates Table–used for bulk updates Table–used for bulk updates Block or page–very commonly used Block or page–very commonly used Record–only requested row; fairly commonly used Record–only requested row; fairly commonly used Field–requires significant overhead; impractical Field–requires significant overhead; impractical Types of locks: Types of locks: Shared lock–Read but no update permitted. Used when just reading to prevent another user from placing an exclusive lock on the record Shared lock–Read but no update permitted. Used when just reading to prevent another user from placing an exclusive lock on the record Exclusive lock–No access permitted. Used when preparing to update Exclusive lock–No access permitted. Used when preparing to update

40. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 40 Deadlock An impasse that results when two or more transactions have locked common resources, and each waits for the other to unlock their resources An impasse that results when two or more transactions have locked common resources, and each waits for the other to unlock their resources Figure 11-12 The problem of deadlock John and Marsha will wait forever for each other to release their locked resources!

41. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 41 Managing Deadlock Deadlock prevention: Deadlock prevention: Lock all records required at the beginning of a transaction Lock all records required at the beginning of a transaction Two-phase locking protocol Two-phase locking protocol Growing phase Growing phase Shrinking phase Shrinking phase May be difficult to determine all needed resources in advance May be difficult to determine all needed resources in advance Deadlock Resolution: Deadlock Resolution: Allow deadlocks to occur Allow deadlocks to occur Mechanisms for detecting and breaking them Mechanisms for detecting and breaking them Resource usage matrix Resource usage matrix

42. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 42 Versioning Optimistic approach to concurrency control Optimistic approach to concurrency control Instead of locking Instead of locking Assumption is that simultaneous updates will be infrequent Assumption is that simultaneous updates will be infrequent Each transaction can attempt an update as it wishes Each transaction can attempt an update as it wishes The system will reject an update when it senses a conflict The system will reject an update when it senses a conflict Use of rollback and commit for this Use of rollback and commit for this

43. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 43 Figure 11-14 The use of versioning Better performance than locking

44. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 44 Data Dictionaries and Repositories Data dictionary Data dictionary Documents data elements of a database Documents data elements of a database System catalog System catalog System-created database that describes all database objects System-created database that describes all database objects Information Repository Information Repository Stores metadata describing data and data processing resources Stores metadata describing data and data processing resources Information Repository Dictionary System (IRDS) Information Repository Dictionary System (IRDS) Software tool managing/controlling access to information repository Software tool managing/controlling access to information repository

45. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 45 Figure 11-15 Three components of the repository system architecture A schema of the repository information Software that manages the repository objects Where repository objects are stored Source: adapted from Bernstein, 1996.

46. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 46 Database Performance Tuning DBMS Installation DBMS Installation Setting installation parameters Setting installation parameters Memory and Storage Space Usage Memory and Storage Space Usage Set cache levels Set cache levels Choose background processes Choose background processes Data archiving Data archiving Input/output (I/O) Contention Input/output (I/O) Contention Use striping Use striping Distribution of heavily accessed files Distribution of heavily accessed files CPU Usage – Monitor CPU load CPU Usage – Monitor CPU load Application tuning Application tuning Modification of SQL code in applications Modification of SQL code in applications Use of heartbeat queries Use of heartbeat queries

47. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall Cost of Downtime 47 Downtime is expensive

48. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 48 Data Availability How to ensure availability How to ensure availability Hardware failures–provide redundancy for fault tolerance Hardware failures–provide redundancy for fault tolerance Loss of data–database mirroring Loss of data–database mirroring Human error–standard operating procedures, training, documentation Human error–standard operating procedures, training, documentation Maintenance downtime–automated and non- disruptive maintenance utilities Maintenance downtime–automated and non- disruptive maintenance utilities Network problems–careful traffic monitoring, firewalls, and routers Network problems–careful traffic monitoring, firewalls, and routers

49. Chapter 11 © 2011 Pearson Education, Inc. Publishing as Prentice Hall 49 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Printed in the United States of America. Copyright © 2011 Pearson Education, Inc. Publishing as Prentice Hall