1. DBMS & TPS
Barbara Russell
MBA 624

2. DBMS
DATA
BASE
MANAGEMENT
SYSTEM

3. DBMS Definition A collection of programs that facilitates
The creation and maintenance of a database or databases
and
The execution of computer programs using the database or databases

4. What then is a Database?
A self-describing collection of integrated records
Self-describing - contains information regarding it’s own structure, called a data dictionary

5. Database Definition A database contains 4 types of information:
User Data
Indexes – represent relationships about the data
Application Metadata – information about the applications that use the database
Data Dictionary or “Metadata” – description of the structure of the database

6. Most Common Databases
Flat File
Relational
Object Oriented

7. Flat File Database
single computer files that store all of the information for a system.
Either a single file or a series of files
Usually comma de-liminated or fixed width
Disadvantage:
Hard to scan – have to look through entire file to find a single record

8. Relational Databases Data stored in a series of tables
Each table stores a discrete piece of data for the system
Tables can be linked (relationships established)

9. Relational Databases SQL – Structured Query Language
common language used to interact with many relational databases.
Recordset – The result of an SQL statement
SAMPLE SQL QUERY
Select Customer.CustomerID, ArtistName fields
From Customer, Artist tables
Where Customer.CustmerID = Artist.ArtistID criteria

10. Object-Oriented Databases
Newer
Designed to store multimedia data such as image and video
Encapsulates all data into different types of objects
Much less common, due to
High price
Complexity
Lack of interoperability standards

11. Components of a Database System
DBMS
Design Tools
Table Creation Tool
Form Creation Tool
Query Creation Tool
Report Creation Tool
Procedural Language Compiler
Developer
Application Programs
Database
DBMS Engine
Run Time
Form Processor
Query Processor
Report Writer
Procedural Language Run Time
Database Contains:
Users’ Data
Metadata
Indexes
Application Metadata
Users
Application Programs
Components of a Database System

12. Job of the DBMS
Manage user requests so that users are free from having to understand where data is physically located and who else might be accessing the data
Handle integrity of the data – i.e. assure the data is accessible and consistently organized
Handle security – i.e. assure only those with appropriate privileges can access the data

13. Common DBMSs
Many types – ranging from small systems that run on PC’s to large systems that run on mainframes
MS Access – popular example of a single or small-group DBMS. Designed to run on PC’s
DBMS that serve requests from multiple users
MS SQL Server
IBM’s DB2
Oracle line

14. QUESTION?
Is Microsoft Excel considered a DBMS?

15. TPS
Transaction
Processing
Systems

16. Transaction Processing System
A type of computer processing in which the computer responds immediately to user requests.
Each request is considered to be a “transaction”.
Requires interaction with the user

17. Transaction Processing System
The opposite of Transaction Processing is Batch Processing
Where a batch of requests is stored then executed all at one time.
Can take place without the user being present.

18. Concurrency Control
Needed to ensure that one user’s work does not inappropriately influence another user’s work.
Either,
A user gets the same result when processing with other users as she would have processing alone or
A user’s work is influenced by other users, but in an anticipated way.

19. Concurrency Control Techniques for managing concurrency control
Atomic Transactions
Resource Locking
Transaction Isolation
Cursor Type
No mechanism ideal for all circumstances All involve tradeoffs

20. Atomicity and Transactions
Transaction – definition.
A transaction is a series of actions to be taken on a database such that either all of the actions are performed successfully or none of them is performed at all.
Often referred to as an Atomic Transaction

21. Why is Atomicity Important?
Consider following example:
You want to move $500 from your savings account to your checking account
The following operations need to occur:
Reduce the savings account by $500
Increase the checking account by $500
What if only one operation completed successfully?

22. How is Atomicity Achieved?
TPS “groups” the operations into a single “transaction”
Does this by copying the data in question, then running the operations on the copied data.
When all commands have successfully been completed, changed data written back to the system in a single operation
If either operation fails, copied data discarded, and an error is reported.

23. Disallow sharing by locking data that are retrieved for update.
Resource Locking
Disallow sharing by locking data that are retrieved for update.

24. Locking
2 basic styles
Optimistic – assumption made that no conflict will occur.
Data is read, transaction is processed, updates issued, then check made to see if conflict occurred.
Pessimistic – assumption made conflict will occur
Locks issued, then transaction processed, then locks freed.

25. Locking Exclusive Lock – locks the item from access of any type
Shared Lock – locks the item from change but not from read

26. Transaction Isolation Level
In addition to locking, most DBMS products support variety of transaction isolation levels.
Isolation level determines how a DBMS places locks.

27. Transaction Isolation Examples

28. CURSOR TYPE
Cursor – pointer into a relation, or more specifically, into a recordset.
To process the rows in a relation, the database application must open the relation and establish a cursor for it.
A single transaction, may have several cursors open at once
2 or more cursors may be open on the same recordset

29. Cursor Type - continued
Maintaining cursors requires significant overhead
To reduce amount of overhead, reduced-overhead cursors are defined.

30. Cursor Type - examples

31. Conclusion Future of DBMS & TPS
Growth in the use of Object Oriented DBMSs
Distributed databases vs. single, large, integrated Databases
TPS will need to work at an “inter-program” level instead of strict client-server model
Growth of Web-based Transaction Systems
HeiTML – programming language that handles transaction processing activities