1. 2010.10.12- SLIDE 1IS 257 - Fall 2010 Database Administration: Security and Integrity University of California, Berkeley School of Information IS 257: Database Management

2. 2010.10.12- SLIDE 2IS 257 - Fall 2010 Security and Integrity Functions in Database Administration Review –MySQL functions and setup Data Integrity Security Management Backup and Recovery

3. 2010.10.12- SLIDE 3IS 257 - Fall 2010 Security and Integrity Functions in Database Administration Review –MySQL functions and setup Data Integrity Security Management Backup and Recovery

4. 2010.10.12- SLIDE 4IS 257 - Fall 2010 SELECT Syntax: –SELECT [DISTINCT] attr1, attr2,…, attr3 as label, function(xxx), calculation, attr5, attr6 FROM relname1 r1, relname2 r2,… rel3 r3 WHERE condition1 {AND | OR} condition2 ORDER BY attr1 [DESC], attr3 [DESC]

5. 2010.10.12- SLIDE 5IS 257 - Fall 2010 SELECT Conditions = equal to a particular value >= greater than or equal to a particular value > greater than a particular value <= less than or equal to a particular value <> or != not equal to a particular value LIKE ‘%wom_n%’ (Note different wild card from Access) opt1 SOUNDS LIKE opt2 IN (‘opt1’, ‘opt2’,…,’optn’) BETWEEN opt1 AND opt2 IS NULL or IS NOT NULL

6. 2010.10.12- SLIDE 6IS 257 - Fall 2010 Aggregate (group by) Functions COUNT(dataitem) COUNT(DISTINCT expr) AVG(numbercolumn) SUM(numbercolumn) MAX(numbercolumn) MIN(numbercolumn) STDDEV(numbercolumn) VARIANCE(numbercolumn) and other variants of these…

7. 2010.10.12- SLIDE 7IS 257 - Fall 2010 Numeric Functions ABS(n) ACOS(n) ASIN(n) ATAN(n) ATAN2(n, m) CEIL(n) COS(n) COSH(n) CONV(n, f- base,t-base) COT(n) ROUND(n) SIGN(n) SIN(n) SINH(n) SQRT(n) TAN(n) TANH(n) TRUNCATE( n,m) DEGREES(n) EXP(n) FLOOR(n) LN(n) LOG(n,b) MOD(n) PI() POWER(n,p)

8. 2010.10.12- SLIDE 8IS 257 - Fall 2010 Character Functions returning character values CHAR(n,…) CONCAT(str1,str2,…) LOWER(char) LPAD(char, n,char2), RPAD(char, n,char2) LTRIM(char, n, cset), RTRIM(char, n, cset) REPLACE(char, srch, repl) SOUNDEX(char) SUBSTR(char, m, n) UPPER(char)

9. 2010.10.12- SLIDE 9IS 257 - Fall 2010 Character Function returning numeric values ASCII(char) INSTR(char1, char2) LENGTH(char) BIT_LENGTH(str) CHAR_LENGTH(str) LOCATE(substr,str) LOCATE(substr,str,po s) and many other variants.

10. 2010.10.12- SLIDE 10IS 257 - Fall 2010 Date functions ADDDATE(dt, INTERVAL expr unit) or ADDDATE(dt, days) ADDTIME(dttm, time) LAST_DAY(dt) MONTH(dt) – YEAR(dt) – DAY(dt) MONTHNAME(dt) NOW() NEW_TIME(d, z1, z2) -- PST, AST, etc. NEXT_DAY(d, dayname) STR_TO_DATE(str,format) SYSDATE()

11. 2010.10.12- SLIDE 11IS 257 - Fall 2010 Diveshop on MySQL Setting up Diveshop on MySQL –Get from class website (Diveshop.sql) –store in your home directory or copy to home directory from /groups/everyone/i257/Diveshop.sql –login to harbinger –start mysql –do \. Diveshop.sql

12. 2010.10.12- SLIDE 12IS 257 - Fall 2010 Capturing results from MySQL Use the \T command in MySQL to put everything you see into a file… –mysql> \T myoutputfilename Logging to file ‘myoutputfilename’ –mysql> SELECT … …output from select command… -- mysql> \t Outfile disabled -- mysql> \q

13. 2010.10.12- SLIDE 13IS 257 - Fall 2010 MySQL and XML When starting Mysql from the command line use the --xml option –harbinger:~> mysql --xml -p ray All output from commands will be in XML form (and when captured the entire resultset will be XML and include the select command)

14. 2010.10.12- SLIDE 14IS 257 - Fall 2010 Security and Integrity Functions in Database Administration Data Integrity (review) Security Management Backup and Recovery

15. 2010.10.12- SLIDE 15IS 257 - Fall 2010 Data Integrity Intrarecord integrity (enforcing constraints on contents of fields, etc.) Referential Integrity (enforcing the validity of references between records in the database) Concurrency control (ensuring the validity of database updates in a shared multiuser environment)

16. 2010.10.12- SLIDE 16IS 257 - Fall 2010 Integrity Constraints (review) The constraints we wish to impose in order to protect the database from becoming inconsistent. Five types –Required data –attribute domain constraints –entity integrity –referential integrity –enterprise constraints

17. 2010.10.12- SLIDE 17IS 257 - Fall 2010 Required Data Some attributes must always contain a value -- they cannot have a NULL value For example: –Every employee must have a job title. –Every diveshop diveitem must have an order number and an item number

18. 2010.10.12- SLIDE 18IS 257 - Fall 2010 Attribute Domain Constraints Every attribute has a domain, that is a set of values that are legal for it to use For example: –The domain of sex in the employee relation is “M” or “F” Domain ranges can be used to validate input to the database

19. 2010.10.12- SLIDE 19IS 257 - Fall 2010 Entity Integrity The primary key of any entity: –Must be Unique –Cannot be NULL

20. 2010.10.12- SLIDE 20IS 257 - Fall 2010 Referential Integrity A “foreign key” links each occurrence in a relation representing a child entity to the occurrence of the parent entity containing the matching candidate (usually primary) key Referential Integrity means that if the foreign key contains a value, that value must refer to an existing occurrence in the parent entity For example: –Since the Order ID in the diveitem relation refers to a particular diveords item, that item must exist for referential integrity to be satisfied.

21. 2010.10.12- SLIDE 21IS 257 - Fall 2010 Referential Integrity Referential integrity options are declared when tables are defined (in most systems) There are many issues having to do with how particular referential integrity constraints are to be implemented to deal with insertions and deletions of data from the parent and child tables.

22. 2010.10.12- SLIDE 22IS 257 - Fall 2010 Insertion rules A row should not be inserted in the referencing (child) table unless there already exists a matching entry in the referenced table Inserting into the parent table should not cause referential integrity problems Sometimes a special NULL value may be used to create child entries without a parent or with a “dummy” parent

23. 2010.10.12- SLIDE 23IS 257 - Fall 2010 Deletion rules A row should not be deleted from the referenced table (parent) if there are matching rows in the referencing table (child) Three ways to handle this –Restrict -- disallow the delete –Nullify -- reset the foreign keys in the child to some NULL or dummy value –Cascade -- Delete all rows in the child where there is a foreign key matching the key in the parent row being deleted

24. 2010.10.12- SLIDE 24IS 257 - Fall 2010 Referential Integrity This can be implemented using external programs that access the database newer databases implement executable rules or built-in integrity constraints (e.g. Access and Oracle)

25. 2010.10.12- SLIDE 25IS 257 - Fall 2010 Enterprise Constraints These are business rule that may affect the database and the data in it –for example, if a manager is only permitted to manage 10 employees then it would violate an enterprise constraint to manage more

26. 2010.10.12- SLIDE 26IS 257 - Fall 2010 Data and Domain Integrity This is now increasing handled by the database. In Oracle or MySQL, for example, when defining a table you can specify: CREATE TABLE table-name ( attr2 attr-type NOT NULL, forbids NULL values attrN attr-type CHECK (attrN = UPPER(attrN) verifies that the data meets certain criteria attrO attr-type DEFAULT default_value); Supplies default values

27. 2010.10.12- SLIDE 27IS 257 - Fall 2010 Referential Integrity Ensures that dependent relationships in the data are maintained. In Oracle or MySQL, for example: CREATE TABLE table-name ( attr1 attr-type PRIMARY KEY, attr2 attr-type NOT NULL, …, attrM attr-type REFERENCES tablename(attrname) ON DELETE CASCADE, … These have many additional options…

28. 2010.10.12- SLIDE 28IS 257 - Fall 2010 Concurrency Control The goal is to support access by multiple users to the same data, at the same time It must assure that the transactions are serializable and that they are isolated It is intended to handle several problems in an uncontrolled system Specifically: –Lost updates –Inconsistent data states during access –Uncompleted (or committed) changes to data

29. 2010.10.12- SLIDE 29IS 257 - Fall 2010 No Concurrency Control: Lost updates Read account balance (balance = $1000) Withdraw $200 (balance = $800) Write account balance (balance = $800) Read account balance (balance = $1000) Withdraw $300 (balance = $700) Write account balance (balance = $700) JohnMarsha ERROR!

30. 2010.10.12- SLIDE 30IS 257 - Fall 2010 Concurrency Control: Locking Locking levels –Database –Table –Block or page –Record –Field Types –Shared (S locks) –Exclusive (X locks)

31. 2010.10.12- SLIDE 31IS 257 - Fall 2010 Concurrency Control: Updates with X locking Lock account balance Read account balance (balance = $1000) Withdraw $200 (balance = $800) Write account balance (balance = $800) Unlock account balance Read account balance (DENIED) Lock account balance Read account balance (balance = $800) etc... JohnMarsha

32. 2010.10.12- SLIDE 32IS 257 - Fall 2010 Concurrency Control: Deadlocks Place S lock Read account balance (balance = $1000) Request X lock (denied) wait... Place S lock Read account balance (balance = $1000) Request X lock (denied) wait... John Marsha Deadlock!

33. 2010.10.12- SLIDE 33IS 257 - Fall 2010 Concurrency Control Avoiding deadlocks by maintaining tables of potential deadlocks and “backing out” one side of a conflicting transaction Normally strict Two-Phase locking (TPL or 2PL) is used. It has the characteristics that –Strict 2PL prevents transactions from reading uncommitted data, overwriting uncommitted data, and unrepeatable reads –It prevents cascading rollbacks (i.e. having to roll back multiple transactions), since eXclusive locks (for write privileges) must be held until a transaction commits

34. 2010.10.12- SLIDE 34IS 257 - Fall 2010 Transaction Control in ORACLE Transactions are sequences of SQL statements that ORACLE treats as a unit –From the user’s point of view a private copy of the database is created for the duration of the transaction Transactions are started with SET TRANSACTION, followed by the SQL statements Any changes made by the SQL are made permanent by COMMIT Part or all of a transaction can be undone using ROLLBACK

35. 2010.10.12- SLIDE 35IS 257 - Fall 2010 Transactions in ORACLE COMMIT; (I.e., confirm previous transaction) SET TRANSACTION READ ONLY; SELECT NAME, ADDRESS FROM WORKERS; SELECT MANAGER, ADDRESS FROM PLACES; COMMIT; Freezes the data for the user in both tables before either select retrieves any rows, so that changes that occur concurrently will not show up Commits before and after ensure any uncompleted transactions are finish, and then release the frozen data when done

36. 2010.10.12- SLIDE 36IS 257 - Fall 2010 Transactions in ORACLE Savepoints are places in a transaction that you may ROLLBACK to (called checkpoints in other DBMS) –SET TRANACTION…; –SAVEPOINT ALPHA; –SQL STATEMENTS… –IF (CONDITION) THEN ROLLBACK TO SAVEPOINT ALPHA; –SAVEPOINT BETA; –SQL STATEMENTS… –IF …; –COMMIT;

37. 2010.10.12- SLIDE 37IS 257 - Fall 2010 Transactions in MySQL START TRANSACTION or BEGIN starts a transaction block (disables autocommit) COMMIT or ROLLBACK will commit the transaction block or return to state before the block was started MySQL may use different underlying database engines – the InnoDB engine also supports SAVEPOINT and ROLLBACK TO SAVEPOINT

38. 2010.10.12- SLIDE 38IS 257 - Fall 2010 Transactions in MySQL (5.0+) START TRANSACTION [WITH CONSISTENT SNAPSHOT] | BEGIN [WORK] COMMIT [WORK] [AND [NO] CHAIN] [[NO] RELEASE] ROLLBACK [WORK] [AND [NO] CHAIN] [[NO] RELEASE] SET AUTOCOMMIT = {0 | 1} The START TRANSACTION and BEGIN statement begin a new transaction. COMMIT commits the current transaction, making its changes permanent. ROLLBACK rolls back the current transaction, canceling its changes. The SET AUTOCOMMIT statement disables or enables the default autocommit mode for the current connection.

39. 2010.10.12- SLIDE 39IS 257 - Fall 2010 MySQL: Explicit locking of tables LOCK TABLES tbl_name [[AS] alias] lock_type [, tbl_name [[AS] alias] lock_type]... lock_type: READ [LOCAL] | [LOW_PRIORITY] WRITE UNLOCK TABLES MySQL enables client sessions to acquire table locks explicitly for the purpose of cooperating with other sessions for access to tables, or to prevent other sessions from modifying tables during periods when a session requires exclusive access to them. A session can acquire or release locks only for itself. One session cannot acquire locks for another session or release locks held by another session.

40. 2010.10.12- SLIDE 40IS 257 - Fall 2010 Security and Integrity Functions in Database Administration Data Integrity Security Management Backup and Recovery

41. 2010.10.12- SLIDE 41IS 257 - Fall 2010 Database Security Views or restricted subschemas Authorization rules to identify users and the actions they can perform User-defined procedures (with rule systems or triggers) to define additional constraints or limitations in using the database Encryption to encode sensitive data Authentication schemes to positively identify a person attempting to gain access to the database

42. 2010.10.12- SLIDE 42IS 257 - Fall 2010 Views A subset of the database presented to some set of users –SQL: CREATE VIEW viewname AS SELECT field1, field2, field3,…, FROM table1, table2 WHERE ; –Note: “queries” in Access function as views

43. 2010.10.12- SLIDE 43IS 257 - Fall 2010 Restricted Views Main relation has the form: Name C_name Dept C_dept Prof C_prof TC J SmithSDept1SCryptographyTS M DoeUDept2SIT SecuritySS R JonesUDept3USecretaryUU U = unclassified : S = Secret : TS = Top Secret

44. 2010.10.12- SLIDE 44IS 257 - Fall 2010 Restricted Views NAMEDeptProf J SmithDept1--- M DoeDept2IT Security R JonesDept3Secretary NAMEDeptProf M Doe--- R JonesDept3Secretary S-view of the data U-view of the data

45. 2010.10.12- SLIDE 45IS 257 - Fall 2010 Authorization Rules Most current DBMS permit the DBA to define “access permissions” on a table by table basis (at least) using the GRANT and REVOKE SQL commands Some systems permit finer grained authorization (most use GRANT and REVOKE on variant views

46. 2010.10.12- SLIDE 46IS 257 - Fall 2010 Security and Integrity Functions in Database Administration Data Integrity Security Management Backup and Recovery

47. 2010.10.12- SLIDE 47IS 257 - Fall 2010 Database Backup and Recovery Backup Journaling (audit trail) Checkpoint facility Recovery manager

48. 2010.10.12- SLIDE 48IS 257 - Fall 2010 Disaster Recovery Planning Testing and Training Procedures Development Budget & Implement Plan Maintenance Recovery Strategies Risk Analysis From Toigo “Disaster Recovery Planning”

49. 2010.10.12- SLIDE 49IS 257 - Fall 2010 Threats to Assets and Functions Water Fire Power Failure Mechanical breakdown or software failure Accidental or deliberate destruction of hardware or software –By hackers, disgruntled employees, industrial saboteurs, terrorists, or others

50. 2010.10.12- SLIDE 50IS 257 - Fall 2010 Threats Between 1967 and 1978 fire and water damage accounted for 62% of all data processing disasters in the U.S. The water damage was sometimes caused by fighting fires More recently improvements in fire suppression (e.g., Halon) for DP centers has meant that water is the primary danger to DP centers

51. 2010.10.12- SLIDE 51IS 257 - Fall 2010 Kinds of Records Class I: VITAL –Essential, irreplaceable or necessary to recovery Class II: IMPORTANT –Essential or important, but reproducible with difficulty or at extra expense Class III: USEFUL –Records whose loss would be inconvenient, but which are replaceable Class IV: NONESSENTIAL –Records which upon examination are found to be no longer necessary

52. 2010.10.12- SLIDE 52IS 257 - Fall 2010 Offsite Storage of Data Early offsite storage facilities were often intended to survive atomic explosions PRISM International directory –PRISM = Professional Records and Information Services Management –http://www.prismintl.org/ Mirror sites (Hot sites)