4.5 Databases Flashcards
(12 cards)
DBMS
A DBMS is a database management system which allows an admin to maintain one or more relational databases. Most of are proprietary (commerical products) however MySQL and SQLite are free. They provide a GUI to allow admins to work efficiently and easily and the ability to modify the data stucture, create indexes, browse data etc.
Database
A structured and organised collection of data used for efficientt storage and retireval of that data.
Composite Primary Key
Used when a single primary key isnt adequate enough to act as a unique identifer for a record.
For example a table of a students classes will have two primary keys, a student ID and a Course ID as one wouldnt suffice, as if it was just student ID and he appeared on that table multiple times, his ID would appear multiple times which is redundant
Data consistency, integrity and redudancy
Data Consistency - all data written must be valid
Data Integrity - refers to the correctness of the data as it must be correct when added and queried
Data Redudancy - repeated data
Redudancy can lead to integrity issues as if a table with 10 of the same reocrds needs a field change then each one has to be manually overwritten which can lead to integrity issues.
Flat File Database
Data stored in one single tables. simple and easy to use for small datasets but becomes inefficient with large data sets
Relational Database
Stored data in multiple tables that are connect thorugh through relationships. Reduces redudandant data, improves data integrity and supports complex queries
Big Data
Big data refers to data sets that are too large or complex for traditional data processing to deal with.
5 V’s
Volume - Huge amount of data being processed
Veracity - Inconsistencies and uncertainy in data whic involves filtering and translating to ensure accuracy
Velocity - High speed of accumulation of data. Big Data can handle real time ensuring rapid data flow from sources.
Variety - Different formats of data (text, video etc) from various sources, Big Data can be structured, semi - structured or unstructured
Value - Extract useful data, goal is to manage valuable data to drivem business decisions
Distrubuted Systems
A system whose componenets are located on different network locations.
+ Scalability: System can handle growing amount of work and can increasing processing power without dropping performace
Vertical Stability involves adding more resources to a single node (e.g upgrading RAM), Horizontal Scalbility involves adding more nodes to the system to distrubute work more evenly
Reliability: If one node fails, other can continue to work, reducing riks of system-wide failure, cooridnating reovering can be hard
Performance - Tasks can be processed in parrallel leading to faster completetion times. Sounds faster in theroy but to do so communication has to be sent across network which cna introduce latency
Flexibility- different parts of the system can be optimised for different tasks
Geographical Distrubution- data and processing power can be placed closer to wheres it needed to reduce latency and improve user experience
Data Warehousing
Where the large amounts of data from various sorces is stored and managed. Put data into consistent form for querying
Data Mining
The process of analysing large volumes of stored data to identify patterns, trends and relationships. Supports decision makings.
Data Dictionary
A component of DBMS that stores the names, defintions and attributes for data elements.
Consistency - Esnrues all data follows the same rules and terminlogy, ensures consistency and intergity in data stored in db
Maintanance - Manages the design structure the helps mapping during design, offers documentation for traceability
