Advanced Database Topics Flashcards
What does the acronym ACID stand for?
Atomicity
Consistency
Isolation
Durability
What does atomicity mean?
Either both operations happen or neither does
What does consistency mean?
Both records/accounts need to be displaying the same information
What does isolation mean?
Other users never see a state in which one line has been performed and not the other
What does durability mean?
Once the operations are acknowledged and performed, they are permanently recorded
What do the letters in the CAP acynonym stand for?
Consistent
Avaliable
Partition Tolerant
What does Brewer’s theorem?
Cannot have all three in CAP at all times
What are BASE systems?
Basically Avaliable for requests
Soft state, change over time
Evenually consistent
What are the variety of CAP options?
Consistent and Avaliable (e.g. classical relational databses)
Consistent and Partition Tolerant
Avaliable and Partition Tolerant
What is sharding?
Sharding refers to the horizontal partitioning of a database
(different rows sit on different servers)
What are some disadvantages of sharding?
Queries become really complex
Reliant on server interconnection
What is the NoSQL movement?
Movement that realises that SQL may not always be the best choice
Give examples of common NoSQL data models?
Key-Value store Column store Document store Object database Graph database
Give an example of a database system that uses key-value store
LevelDB, Oracle NoSQL
