1 Database II Introduction to Database Administration Muhammad Asghar Khan
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 1/21
1
Database II
Introduction
toDatabase Administration
Muhammad Asghar Khan
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 2/21
2
Introduction
Data and information are resources that are valuablefor organizations like other financial or other physical
resources
Database administration activities have beendeveloped to help achieve organizations goals for the
effective management of data
Effective data administration provides support for
managerial decision making at all levels in the
organization
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 3/21
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 4/21
4
Database Administration (1/2)
Database Administration is a technical activity that isresponsible for physical database design and for
dealing with technical issues such as security
enforcement, database performance, backup and
recovery
The DBA should be involved in every phase of
database development , from database planning
through maintenance and modification
DBA carries through the standard and procedures
developed by DA
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 5/21
5
Database Administration (1/2)
DBA can also act as DA
DBA needs broad technical background in
Hardware Architectures,
Data Processing,
Database Development Life Cycle,
Strong Design and Data Modeling Skills
Managerial Skills
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 6/21
6
DA vs. DBA
Figure below depicts the relationship b/w DA andDBA
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 7/21
7
DBA Functions and Responsibilities (1/15)
To ensure that an organization's data and databasesare useful, usable, available, and correct requires theDBA to perform a variety of tasks in a variety of areas
These areas include:
1. Database Design,
2. Performance Monitoring and Tuning,
3. Database Availability,
4. Security and Authorization,
5. Backup and Recovery,
6. Data Integrity,
7. Release Migration
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 8/21
8
DBA Functions and Responsibilities (2/15)
1. Database Design The DBA must understand and adhere to sound relational
design practices
The DBA must understand both relational theory and thespecific implementation of the RDBMS he's using to
create the database
Database design requires a sound understanding of
conceptual and logical data modeling techniques
The ability to create and interpret ERD is essential to
designing a relational database
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 9/21
9
DBA Functions and Responsibilities (3/15)
The DBA must be able to transform a logical data model
into a physical database implementation
A poor relational design can result in poor performance
2. Performance Monitoring and Tuning
What is meant by database performance?
The rate at which the DBMS supplies the information can be termed as database performance
Five factors influence database performance: workload,
throughput, resources, optimization, and contention
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 10/21
10
DBA Functions and Responsibilities (4/15)
Workload
It is defined as the work demanded from RDBMS
It is a combination of online transactions, batch jobs, ad hoc
queries, data warehousing, analytical queries, and commands
directed through the system at any given time
Workload can fluctuate drastically from day to day, hour to hour,
minute to minute, and even second to second
Sometimes workload can be predicted (such as heavy month-end processing of payroll, or very light access after 7:30 P.M., when
most users have left for the day), but at other times it is
unpredictable
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 11/21
11
DBA Functions and Responsibilities (5/15)
Throughput It defines the overall capability of the computer hardware and
software to process data
It is a composite of I/O speed, CPU speed, parallel capabilities of the machine, and the efficiency of the operating system and system
software Resources
The hardware and software tools at the disposal of the system areknown as the resources of the system
Optimization
It refers to the analysis of database requests with query costformulas to generate efficient access paths to data
All types of systems can be optimized, but relational queries areunique in that optimization is primarily accomplished internal to theDBMS
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 12/21
12
DBA Functions and Responsibilities (6/15)
Contention
It is the condition in which two or more components of the
workload are attempting to use a single resource in a conflicting
way (for example, dual updates to the same piece of data)
As contention increases, throughput decreases
Therefore, database performance can be defined as the
optimization of resource usage to increase throughput and
minimize contention, enabling the largest possible
workload to be processed
3. Database Availability
The availability of data and databases is often closely
related with performance
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 13/21
13
DBA Functions and Responsibilities (7/15)
The first component of availability is keeping the DBMS up and
running
Database clustering technologies provide failover techniques that help
to reduce downtime
Nevertheless, such technology usually requires more skill and
planning to implement
4. Database Security and Authorization
Once the database is designed and implemented, programmers andusers will need to access and modify the data
Only authorized programmers and users should have access
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 14/21
14
DBA Functions and Responsibilities (8/15)
It is the responsibility of the DBA to ensure that data is
available only to authorized users
The DBA works with the internal security features of the
DBMS in the form of SQL GRANT and REVOKE
statements
Database security can be enforced in other ways as well.
For example, views can be created that block access to
sensitive data by end users and programmers
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 15/21
15
DBA Functions and Responsibilities (9/15)
5. Backup and Recovery
The DBA must be prepared to recover data in the event of a problem
"Problem" can mean anything from a system glitch or program error
to a natural disaster that shuts down an organization
The majority of recoveries today occur as a result of application
software error and human error
In fact, analyst estimates indicate that 80% of application errors are
due to software failures and human error
The DBA must be prepared to recover data to a usable point, no
matter what the cause, and to do so as quickly as possible
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 16/21
16
DBA Functions and Responsibilities (10/15)
Type of data recoveries can be Recover to Current, Point-
in-Time Recovery, Transaction Recovery,
Recover to Current
Usually in the face of a major shutdown
The end result of the recovery is that the database is brought back to
its current state at the time of the failure
Point-in-Time Recovery
Usually deals with an application-level problem Conventional techniques to perform a point-in-time recovery
remove the effects of all transactions since a specified point in time
This can cause problems if valid transactions occurred during that
timeframe that still need to be applied
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 17/21
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 18/21
18
DBA Functions and Responsibilities (12/15)
6. Data Integrity A database must be designed to store the correct data in
the correct way without that data becoming damaged or
corrupted
Physical Aspect of Data Integrity
Can be implemented using DBMS features such as domains and
data types
Most relational DBMS products provide the following types of
constraints:
Primary Key constraints
Referential constraints
Unique constraints
Check constraints
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 19/21
19
DBA Functions and Responsibilities (13/15)
Semantic Aspect of Data Integrity
It is more difficult to control and less easily defined
An example of semantic integrity is the quality of the data in the
database
Procedures and practices need to be in place to ensure data quality.
For example, a customer database that contains a wrong address or
phone number in 25% of the customer records is an example of a
database with poor quality
Data quality is encouraged through proper application code, sound
business practices, and specific data policies
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 20/21
20
DBA Functions and Responsibilities (14/15)
DBMS Internal Aspect of Data Integrity
The DBMS relies on internal structures and code to maintain links,
pointers, and identifiers
Internal DBMS integrity is essential in the following areas:
Index consistency
An index is really nothing but an ordered list of pointers to data in
database tables
Pointer consistency
Sometimes large multimedia objects are not stored in the same
physical files as other data.
Therefore, the DBMS requires pointer structures to keep the
multimedia data synchronized to the base table data
8/8/2019 Week10 - DB Admin
http://slidepdf.com/reader/full/week10-db-admin 21/21
21
DBA Functions and Responsibilities (15/15)
Backup consistency
Some DBMS products occasionally take improper backup copies
that effectively cannot be used for recovery
It is essential to identify these scenarios and take corrective actions
7. DBMS Release Migration
The DBA is also responsible for managing the migrationfrom release to release of the DBMS
DBMS products change quite frequently²new versions
are usually released every year or so