Transaction Processing Systems Flashcards
What is a transaction? /2
A transaction is a series of events important to an organisation that involve:
- request
- acknowledgement
- action
- outcome
An example is ordering a product or purchasing an item
What is the components of a transaction processing system? /5
- purpose
- data
- information technology
- processes
- participants
Two outcomes of a transaction? /2
- complete success
- complete failure
Define Batch Processing, Explain Process, Provide Examples, Advantages and Disadvantages? /6
Batch processing is the collection and storage of data for processing at a scheduled time or when there is sufficient data.
Transaction collected and put into batches or groups»_space;> Transaction File created (contains all data before submitted for processing)»_space;> Transaction file is stored»_space;> Transactions processed and master file updated periodically
Examples: Clearing cheques, payroll processing
Advantages: can be run as a regularly scheduled event, can be run as a fully automated process without need of a human operator
Disadvantages: does not provide data that are full current hence can be out of date, will stop processing if error is detected in any of the tasks, must have exclusive access and control over its data files
Define Real Time Processing, Explain Process, Provide Examples, Requirements Needed? /6
Real time processing immediate processes the data when requested hence everything is up to date.
Processing occurs as the transactions arrive and not delayed like batch processing. Each transaction must be completed within a reasonable amount of time or the user must be notified.
Examples: OLTP (Online Transaction Processing )
Requirements needed are faster direct access to secondary storage, large amount of RAM to allow common processes to be consistent, secure communication links, quick processor
ACID Properties include: /4
Atomicity- All events within a transaction must complete successfully or none at all. e.g airline reservation using credit card
Consistency- Ensures that transactions take data from one consistent state to another. e.g no. reserved seats vs no. tickets issued
Isolation- Allows transactions to process data without interfering with or being influenced by other transactions
Durability- Ensures committed transactions are permanent. All changes written from RAM to permanent storage before transaction is considered to be committed.
Types of TPS? /5
- Web based
- Non web based
- Online Real Time
- Batch
- Systems that appear in real time but actual updating is batch processing. Example: credit cards, deposits ATM
Identify and Describe storage of digital data in database files? /6
Sequential data storage: Stores data in a set sequence and either uses Linear search (unsorted&sorted) or Binary search (sorted)
Indexed Sequential Storage: Made of a main data file and separate smaller index file. Index file contains the key field value and location of every data record in the main file. Can be searched using linear & binary search. If the main file is sorted or content is added / edited then the index file must be altered.
Hashed File Storage: Divides data storage area into a number of different locations and give each location an identifying number. Dividing the key filed value of the designated rerecord by the number of storage locations leaves a remainder. The remainder becomes the location number for the record. Very FAST at locating records in LARGE databases.
Systems to store paper records of transactions? /6
Paper records have several disadvantages
Storing paper is bulky and requires lots of space
A separate index or catalogue must be maintained to locate documents
Difficult to manually find all occurrences of text in multiple documents
Sorting large quantities of paper documents is slow and unreliable
Paper documents can be converted to digital by:
Document imaging
Optical Character Recognition (OCR)
