Transcript - Courses - University of California, Berkeley

Data Administration and Database
Administration
University of California, Berkeley
School of Information Management
and Systems
SIMS 257: Database Management
IS 257 - Fall 2002
2002.11.05- SLIDE 1
Lecture Outline
• Final Project Requirements
• Review
– Fourth Generation Languages
– Object-Relational Extensions to SQL
• Database Administration
IS 257 - Fall 2002
2002.11.05- SLIDE 2
Final Project Requirements
• See WWW site:
– http://sims.berkeley.edu/courses/is257/f02/index.html
• Report on personal/group database including:
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Database description and purpose
Data Dictionary
Relationships Diagram
Sample queries and results (Web or Access tools)
Sample forms (Web or Access tools)
Sample reports (Web or Access tools)
Application Screens or pages (Web or Access tools)
In-class report on database
IS 257 - Fall 2002
2002.11.05- SLIDE 3
Fourth Generation Languages
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1st Generation -- Machine Language
2nd Generation -- Assembly Languages
3rd Generation -- High-Level Languages
4th Generation -- Non-Procedural
Languages
• 5th Generation -- ?? Knowledge-based ??
Natural Language ??
• Where do Object-Oriented Languages
fit??
IS 257 - Fall 2002
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Components of a 4GL
Application
Parameters
Interpreter
IS 257 - Fall 2002
for building routine applications…
Data
Specification
Report
Specification
Screen
Specification
Rules
Specification
Procedural
facility
Feedback
Testing
tools/debugger
Optimizing
compiler
2002.11.05- SLIDE 5
Natural Language
• Advantages of using NL
– It encourages untrained users to start
– It encourages upper-management use of
computers
– It reduces the time taken learning complex
syntax
– It lessens the frustration, bewilderment and
anger caused by BAD COMMAND responses
– It is likely to extend greatly the usage of
computers
James Martin, Fourth Generation Languages, 1985
IS 257 - Fall 2002
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Natural Language
Disadvantages of using NL
• It lacks precision
• It is not good for
expressing precise
and complex logic
• It is not good for
expressing neat
structures
• It encourages
semantic overshoot
Appropriate response to the
disadvantage
• It should be combined
with other dialogue
contructs that aid in
the representation of
precise logic and
structures
James Martin, Fourth Generation Languages, 1985
IS 257 - Fall 2002
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Natural Language
Disadvantages of using NL
• It takes substantial
time to key in
sentences
• Ambiguities are
possible
• Substantial
processing is needed
Appropriate response to the
disadvantage
• Sentences and words can
be abbreviated
• Speech input as well as
typed input will be used
• The computer should
detect and resolve
ambiguities
• The processing should be
on PC workstations.
Processing is dropping
rapidly in cost.
James Martin, Fourth Generation Languages, 1985
IS 257 - Fall 2002
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Assumptions and Issues
• Why 4GLs?
– Are they still appropriate?
– Are they still useful?
• Is Cold Fusion a 4GL?
• What about PHP?
• Who needs them?
IS 257 - Fall 2002
2002.11.05- SLIDE 9
Object Relational Data Model
• Class, instance, attribute, method, and
integrity constraints
• OID per instance
• Encapsulation
• Multiple inheritance hierarchy of classes
• Class references via OID object
references
• Set-Valued attributes
• Abstract Data Types
IS 257 - Fall 2002
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Object-Relational SQL in ORACLE
• CREATE (OR REPLACE) TYPE typename
AS OBJECT (attr_name, attr_type, …);
• CREATE TABLE OF typename;
IS 257 - Fall 2002
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Example
• CREATE TYPE ANIMAL_TY AS OBJECT
(Breed VARCHAR2(25), Name
VARCHAR2(25), Birthdate DATE);
• Creates a new type
• CREATE TABLE Animal of Animal_ty;
• Creates “Object Table”
IS 257 - Fall 2002
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Constructor Functions
• INSERT INTO Animal values
(ANIMAL_TY(‘Mule’, ‘Frances’,
TO_DATE(‘01-APR-1997’, ‘DD-MMYYYY’)));
• Insert a new ANIMAL_TY object into the
table
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Selecting from an Object Table
• Just use the columns in the object…
• SELECT Name from Animal;
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More Complex Objects
• CREATE TYPE Address_TY as object (Street
VARCHAR2(50), City VARCHAR2(25), State
CHAR(2), zip NUMBER);
• CREATE TYPE Person_TY as object (Name
VARCHAR2(25), Address ADDRESS_TY);
• CREATE TABLE CUSTOMER (Customer_ID
NUMBER, Person PERSON_TY);
IS 257 - Fall 2002
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What Does the Table Look like?
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DESCRIBE CUSTOMER;
NAME
TYPE
----------------------------------------------------CUSTOMER_ID
NUMBER
PERSON
NAMED TYPE
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Inserting
• INSERT INTO CUSTOMER VALUES (1,
PERSON_TY(‘John Smith’,
ADDRESS_TY(‘57 Mt Pleasant St.’, ‘Finn’,
‘NH’, 111111)));
IS 257 - Fall 2002
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Selecting from Abstract Datatypes
• SELECT Customer_ID from CUSTOMER;
• SELECT * from CUSTOMER;
CUSTOMER_ID PERSON(NAME, ADDRESS(STREET, CITY, STATE ZIP))
--------------------------------------------------------------------------------------------------1
PERSON_TY(‘JOHN SMITH’, ADDRESS_TY(‘57...
IS 257 - Fall 2002
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Selecting from Abstract Datatypes
• SELECT Customer_id, person.name from
Customer;
• SELECT Customer_id,
person.address.street from Customer;
IS 257 - Fall 2002
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Updating
• UPDATE Customer SET
person.address.city = ‘HART’ where
person.address.city = ‘Briant’;
IS 257 - Fall 2002
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Functions
• CREATE [OR REPLACE] FUNCTION
funcname (argname [IN | OUT | IN OUT]
datatype …) RETURN datatype (IS | AS)
{block | external body}
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TRIGGERS
• Create TRIGGER UPDATE_LODGING
INSTEAD OF UPDATE on
WORKER_LODGING for each row BEGIN
• if :old.name <> :new.name then update
worker set name = :new.name where
name = :old.name;
• end if;
• if :old.lodging <> … etc...
IS 257 - Fall 2002
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Today
• Traditional and Current Data
Administration
• Traditional and Current Database
Administration
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Changes in Traditional Roles
• This is being driven by rapid changes in
– Technology
– Platforms (e.g., Micro vs. Mainframe vs.
Server)
– Organizational Structure
• We will focus on the core functions and
tasks of these roles (traditional or current)
IS 257 - Fall 2002
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Terms and Concepts (trad)
• Data Administration
– Responsibility for the overall management
of data resources within an organization
• Database Administration
– Responsibility for physical database design
and technical issues in database
management
• These roles are often combined or
overlapping in some organizations
IS 257 - Fall 2002
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Terms and Concepts (trad)
• DA
– Data adminstrator - person responsible for the
Data Administration function in an
organization
– Sometimes may be the CIO -- Chief
Information Officer
• DBA
– Database Administrator - person responsible
for the Database Administration Function
IS 257 - Fall 2002
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Database System Life Cycle
Database
Planning
Database
Analysis
Growth &
Change
Operation &
Maintenance
Database
Design
Database
Implementation
Note: this is a different version of this
life cycle than discussed previously
IS 257 - Fall 2002
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Database Planning
• Development of a strategic plan for
database development that supports the
overall organization’s business plan
• DA supports top management in
development of this plan
• The result of this stage is an enterprise
data model
IS 257 - Fall 2002
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Database Planning: DA & DBA functions
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Develop corporate database strategy (DA)
Develop enterprise model (DA)
Develop cost/benefit models (DA)
Design database environment (DA)
Develop data administration plan (DA)
IS 257 - Fall 2002
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Database Analysis
• This is the process (discussed previously) of
identifying data entities currently used by the
organization, precisely defining those entities
and their relationships, and documenting the
results in a form that can support the follow-on
design phase
• Must also identify new data elements or changes
to data elements that will be required in the
future
• The result of this phase is the Conceptual Data
Model -- usually represented as an ER diagram
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Database Analysis: DA & DBA functions
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Define and model data requirements (DA)
Define and model business rules (DA)
Define operational requirements (DA)
Maintain corporate Data Dictionary (DA)
IS 257 - Fall 2002
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Database Design
• Purpose of the design phase is the
development of the logical database
design that will serve the needs of the
organization and the physical design
implementing the logical design
• In relational systems the outcome is
normalized relations, and the data
definition for a particular database
systems (including indexes, etc.)
IS 257 - Fall 2002
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Design 2: Physical Creation
• Development of the Physical Model of the
Database
– data formats and types
– determination of indexes, etc.
• Load a prototype database and test
• Determine and implement security, privacy
and access controls
• Determine and implement integrity
constraints
IS 257 - Fall 2002
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Database Design: DA &DBA functions
• Perform logical database design (DA)
• Design external models (subschemas)
(DBA)
• Design internal model (Physical design)
(DBA)
• Design integrity controls (DBA)
IS 257 - Fall 2002
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Database Implementation
• Database design gives you an empty
database
• Load data into the database structure
• Convert existing data sets and
applications to use the new database
– May need programs, conversion utilities to
convert old data to new formats.
• Outcome is the actual database with its
data
IS 257 - Fall 2002
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Database Implementation DA & DBA functions
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Specify database access policies (DA & DBA)
Establish Security controls (DBA)
Supervise Database loading (DBA)
Specify test procedures (DBA)
Develop application programming standards
(DBA)
• Establish procedures for backup and recovery
(DBA)
• Conduct User training (DA & DBA)
IS 257 - Fall 2002
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Operation and Maintenance 1: Operations
• Users are responsible for updating the
database, DA and DBA are responsible for
developing procedures that ensure the
integrity and security of the database
during the update process.
• Specific responsibility for data collection,
editing and verification must be assigned
• Quality assurance must be practiced to
protect and audit the database quality.
IS 257 - Fall 2002
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Operation and Maintenance 2: Maintenance
• The ongoing process of updating the database
to keep it current
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adding new records
deleting obsolete records
changing data values in particular records
modifying relation structures (e.g. adding new fields)
• Privacy, security, access control must be in
place.
• Recovery and Backup procedures must be
established and used
IS 257 - Fall 2002
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Operation and Maintenance: DA & DBA functions
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Monitor database performance (DBA)
Tune and reorganize databases (DBA)
Enforce standards and procedures (DBA)
Support users (DA & DBA)
IS 257 - Fall 2002
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Growth & Change
• Change is a way of life
– Applications, data requirements, reports, etc.
will all change as new needs and
requirements are found
– The Database and applications and will need
to be modified to meet the needs of changes
to the organization and the environment
– Database performance should be monitored
to maintain a high level of system
performance
IS 257 - Fall 2002
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Growth & Change: DA & DBA functions
• Implement change control procedures (DA
& DBA)
• Plan for growth and change (DA & DBA)
• Evaluate new technology (DA & DBA)
IS 257 - Fall 2002
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Functions in Database Administration
• Planning and Design (we have already
looked at theses processes in detail)
• Data Integrity
• Backup and Recovery
• Security Management
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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)
IS 257 - Fall 2002
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No Concurrency Control: Lost updates
John
• Read account
balance (balance =
$1000)
• Withdraw $200
(balance = $800)
• Write account
balance (balance =
$800)
IS 257 - Fall 2002
Marsha
• Read account
balance (balance =
$1000)
• Withdraw $300
(balance = $700)
• Write account
balance (balance =
$700)
ERROR!
2002.11.05- SLIDE 44
Concurrency Control: Locking
• Locking levels
– Database
– Table
– Block or page
– Record
– Field
• Types
– Shared (S locks)
– Exclusive (X locks)
IS 257 - Fall 2002
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Concurrency Control: Updates with X locking
John
• Lock account balance
• Read account balance
(balance = $1000)
• Withdraw $200 (balance
= $800)
• Write account balance
(balance = $800)
• Unlock account balance
IS 257 - Fall 2002
Marsha
• Read account balance
(DENIED)
• Lock account balance
• Read account balance
(balance = $800)
• etc...
2002.11.05- SLIDE 46
Concurrency Control: Deadlocks
John
• Place S lock
• Read account
balance (balance =
$1000)
• Request X lock
(denied)
• wait ...
Marsha
• Place S lock
• Read account
balance (balance =
$1000)
• Request X lock
(denied)
• wait...
IS 257 - Fall 2002
Deadlock!
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Concurrency Control
• Avoiding deadlocks by maintaining tables
of potential deadlocks and “backing out”
one side of a conflicting transaction
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Database Security
• Views or restricted subschemas
• Authorization rules to identify users and
the actions they can perform
• User-defined procedures (and rule
systems) 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
IS 257 - Fall 2002
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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 <where clause>;
– Note: “queries” in Access function as views
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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
IS 257 - Fall 2002
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Database Backup and Recovery
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Backup
Journaling (audit trail)
Checkpoint facility
Recovery manager
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Disaster Recovery Planning
Risk
Analysis
Recovery
Strategies
Plan
Maintenance
Testing and
Training
Budget &
Implement
Procedures
Development
From Toigo “Disaster Recovery Planning”
IS 257 - Fall 2002
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Threats to Assets and Functions
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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
IS 257 - Fall 2002
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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
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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
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Offsite Storage of Data
• Early offsite storage facilities were often
intended to survive atomic explosions
• PRISM International directory
• Mirror sites (Hot sites)
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