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Final Exam
S3o7
92
Internet/New Media
Undergraduate 3
04/25/2013
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Term
Miniworld
 Definition
–Some part of the world about which information is stored
–Provides a mechanism to scope a problem area
Term
Metadata
 Definition
Data about data
Term
Four components of Database system
 Definition

1. database

2. software

3. hardware

4. people
Term
Database
 Definition
•An organized collection of logically-
related persistent data 
Term
Software
 Definition

Used to

1. Define data types

2. populate data

3. manipulate data

4. control security
Term
Largest DBMS software vendors
 Definition

1. Oracle

2. IBM

3. Microsoft
Term
Processor
 Definition
–Supports the execution of the database system software. 
Term
Storage
 Definition
–Primary: main memory/ random access memory (RAM) and cache
–Secondary: Magnetic Disks
–Tertiary: Tapes
Term
Application programmers
 Definition
–Responsible for writing application
programs that use the database typically
in a language like C, Java etc.
Term
Database Administrators
 Definition
–Manage the DBMS use and ensure that
the database is functioning properly
Term
Database designer
 Definition
–Design database structure, standards for
data in business units, architects 
Term
Data Steward
 Definition
–Business manager is responsible for
quality of data
Term
End Users
 Definition
–Interact with the system from online
workstations or terminals
Term
Phases of database
 Definition

1. requirements analysis

2. conceptual design

3. logical design

4. physical design = schema

5. implementation = database

6. Maintenance = evolving database
Term
File
 Definition
Collection of related records
Term
Field
 Definition
Group of characters with meaning
Term

Record

 

 Definition

Record: Logically connected set of one or more fields
Term
Problems with File Based Systems
 Definition
•Limited data sharing
•Program-data dependence
•Duplication of data
•Lengthy development times
•Excessive program maintenance
Term
Benefits of DBMS
 Definition
–Program-data independence
–Minimal data redundancy
–Improved data consistency
–Improved data sharing
–Enforcement of standards
–Improved data quality
–Increased productivity of application development
Term
Information Systems Architecture (ISA)
 Definition
Blueprint for the information systems in an organization
Term
Information Engineering and its steps
 Definition
Formal methodology for developing ISA
Includes 4 steps: planning, analysis, design and implementation
Term
ISA Diagram components
 Definition

1. data

2. processes

3. network

4. people

5. events and points in time

6. reasons for events
Term
IS Planning
 Definition
  • Identify strategic planning factors
  • identify corporate planning objects
  • Develop enterprise model
Term
ANSI/SPARC
 Definition
[image]
Term
Physical Data Independence
 Definition
The capability to change the physical storage structure without having to change conceptual schemas.
Term
Logical Data Independence
 Definition
The capability to change the conceptual schema without having to change external schemas.
Term
Data integrity
 Definition
accuracy and correctness of data in the database.
Term
Domain Constraint
 Definition
A type constraint is just an enumeration of the legal values of the type
Term
Candidate Key only if:
 Definition
Uniqueness:
No legal value of R ever contains two distinct tuples with the same value for K.
Irreducibility:
No proper subset of K has the uniqueness property.
Term
Super key
 Definition
Any superset of a candidate key is a super key.
A super key has the uniqueness property but not necessarily the irreducibility property.
Term
Key constraint
 Definition
No two tuples can have the same value of primary key
Rationale
Each tuple should be identifiable
Primary key is used identify a tuple
Term
Entity Constraint
 Definition
No primary key value can be NULL
Term
Referential Integrity constraint
 Definition
Attributes of FK in R1 must have the same domain as the PK attribute of another relation R2
Term
Insert?
 Definition
Can violate any of four integrity constraints
Domain Constraint
Term
Delete?
 Definition
Can violate
Referential Integrity
Term
Update
 Definition
Can violate any of four integrity constraints
Term
1 NF
 Definition
Relation has no multi-valued attributes
Term
2 NF
 Definition
in 1 NF, no partial key dependencies
Term
3 NF
 Definition
in 2 NF, no transitive dependencies
Term
Why normalization?
 Definition
adequate performance
data integrity
security
Term
When to use indexes?
 Definition
1.Tables are large
2. attributes that appear in WHERE, ORDER BY and GROUP BY
3. significant variety in the values of attributes
Term
Horizontal partitioning
 Definition
partitioning the table into no.of smaller tables on the basis of rows. Eg: In an employee table, employees with salary less than $10,000 will be partitioned into different table.
Term
Vertical partitioning
 Definition
dividing the table based on the different columns. Eg: In the same employee table, retrieving oly the name and contact number of all the employees into a different table.
Term
SQL
 Definition
Structured Query Language
Term
DDL
 Definition
Define the database
CREATE, ALTER and DROP a TABLE, VIEW or INDEX
Term
DML
 Definition
Manipulate the data in an existing database
INSERT, UPDATE, DELETE
SELECT, i.e., query
Term
DCL
 Definition
Control user access to an existing database
GRANT and REVOKE
Term
sql: Alter table
 Definition
ALTER TABLE [ADD ]
Term
sql:Insert
 Definition
INSERT INTO table name
column name
VALUES values
Term
sql:Update
 Definition
DELETE FROM table name[WHERE];
Term
sql:Delete
 Definition
UPDATE table name SET ,… [WHERE ];
Term
sql: group by
 Definition
SELECT color, SUM(weight)
FROM parts
GROUP BY color;
Term
equi-join (inner-join)
 Definition
FROM department, employee
WHERE department.dept# = employee.dept#;

Columns are repeated
Tuples in a relation R without a matching tuple in a relation S are eliminated
Term
cartesian product
 Definition
SELECT *
FROM department, employee;
Term
Natural join
 Definition
SELECT department.dept#, dname, budget, emp#, ename, salary
FROM department, employee
WHERE department.dept# = employee.dept#;

Columns are NOT repeated
Tuples in a relation R without a matching tuple in a relation S are eliminated
Term
Outer Join
 Definition
A row in one table does not have a matching row in another table
Produces rows that do not have matching values in common columns
NULL values appear where there is not a match
Term
Self Join
 Definition
Select e.ename, mgr.ename as Mgr_name
from employee e, employee mgr
where e.mgrid = mgr.eid;

Tuples in a relation R are joined with themselves
Term
Data administration
 Definition
Custodian of organization’s data
Overall management of data sources
Establishes standards and procedures related to
Term
Database administration
 Definition
Responsible for technical issues related to security, database performance and backup and recovery
Implements the standards and procedures established by the data administrator
Involved in every phase of database design
Provide support to end-users involved in design of databases
Term
Integrity Controls
 Definition
Enforce desirable database conditions
Term
Authorization Rules
 Definition
controls that restrict actions that people may take when they access data
Term
User-defined procedures
 Definition
Password and procedure name need to be specified
Procedure invokes a series of questions (e.g., mother’s maiden name)
Term
Encryption
 Definition
Encoding or scrambling of data
Term
Authentication schemes
 Definition
Identify the people (physical or behavioral traits) who are accessing the data sources
e.g. biometric devices, voice prints
Term
Transaction
 Definition
A logical unit of data processing that includes one or more database access/update operations

Atomic unit of work that is completed in entirety or not done at all
Term
A transaction can include two basic database access operations:
 Definition
read_item and write_item
Term
Commit
 Definition
end previous transaction
Term
abort
 Definition
abort transaction
Term
roll back
 Definition
failed transaction
Term
Properties of a transaction
 Definition
1.Atomicity
2. consistency
3. isolation
4. durability
Term
Journalizing facility
 Definition
Audit trail of transaction
Term
Checkpoint facility
 Definition
Synchronize transaction log and database
DBMS writes checkpoint record to log file
Snapshot of database
Term
Recovery manager
 Definition
Module of DBMS that helps restore database to correct condition
Term
Database Change log
 Definition
before and after images of records
Term
recovery procedure: switch
 Definition
database is mirrored
Term
recovery procedure: restore/run
 Definition
reprocess day’s transactions against backup copy of database
Term
recovery procedure: backward recovery
 Definition
DBMS backs out or undoes the unwanted changes
Term
recovery procedure: forward recovery
 Definition
start with the earlier copy of database
apply good transactions to move the database to later stage
Term
Serializable
 Definition
A schedule is serializable if its result is equivalent to some serial schedule
Term
Concurrency Problem: Lost update
 Definition
Also called write-write conflict
Two transactions that access the same database item have operations interleaved that makes the value of some database item incorrect
Term
Concurrency Problem: dirty read
 Definition
Read values from a transaction that fails
Also called write-read problem because a data item that is written (but not committed) by one transaction is read by another transaction
Term
Concurrency Problem: unrepeateable read
 Definition
A transaction reads an item twice and in between these two read the item has changed
Also called read-write problem because a data item that is read by one transaction is written (changed) by another transaction
Term
Concurrency control: pessimistic method Locking
 Definition
A lock guarantees exclusive use of data item to a current transaction
Lock Granularity
Term
Concurrency control: Optimistic method Versioning
 Definition
1. read phase (make own copy)
2. validation phase (changes will not affect integrity and consistency)
3. write phase (no conflict, changes made)
Term
Lock Granularity
 Definition
Specifies what is locked, i.e., database, table, page (typically 4K), row or cell
Term
Types of lock
 Definition
1. Binary: locked, unlocked - no, some T can use a data item
2. Shared/exclusive - concurrent transactions are given a read access to a data item, write permission on data item is given if data item has no other locks
Term
Binary lock
 Definition
Transaction T must issue lock (X) before read (X) or write (X)
A transaction T must issue unlock (X) after read (X) and write (X) is completed in T
Term
issues with binary lock
 Definition
The resulting transaction may not be serializable
Deadlock
Term
Deadlock
 Definition
Two transactions wait for each other to release locks
Term
Deadlock control
 Definition
Deadlock prevention: DBMS look ahead (deadlock graphs)
Deadlock detection: waits-for-graph tests deadlock and time-out (abort) one transaction
Deadlock avoidance: transaction must obtain all locks before it can be executed
Term
2-PL (Phase locking)
 Definition
defines how transactions acquire and relinquish locks
ensures serializability

Two phases
Growing Phase: acquire locks without unlocking
Shrinking Phase: transaction releases locks and cannot acquire locks
Term
Data as asset
 Definition
Intangibility (Yes/No)
Nonfungibility (No)
Fragility (Yes)
Valuation (Yes, difficult)

Consumability (No)
sharability (Yes)
Copyability (yes)
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