DAT Tools Flashcards
What is the difference between Declarative and Imperative languages?
Declarative - You define the outcome, not how to achieve it. The system chooses the step order and path. Code can be repeated as many times as necessary.
Imperative - The system carries out the precise steps in the order you direct it to.
What is R?
An object oriented programming language.
All commands are functions, often having many default arguments.
What is Python?
An open-source, general-purpose language.
It’s abstracted from computer architecture (more logical to read).
Interpreted, not compiled language (runs line by line)
What are the four Data Structures in Python?
List - Heterogeneous collection. Mutable (can be changed).
Tuple - Immutable list, ordered.
Dictionary - Collections of key-value pairs.
Sets - Collections of unique objects. Unordered and mutable.
What does ACID refer to?
Atomicity - Multiple options treated as single entity, all completed or none.
Consistency
Isolation - Concurrent operations don’t influence eachother.
Durability
What does BASE refer to?
Basic Availability - Appears working, but some data may be unavailable.
Soft-state - Each store isn’t always consistent.
Eventual consistency - Stores not consistent will eventually catch-up.
Often used in Big Data.
How many records can Excel handle and display?
1 million records can be displayed, 10 million can be handled.
Define NOSQL
It is a database not solely using SQL querying.
What is a Document Datastore?
Data stored and queried as JSON like documents. Documents can be nested within documents.
What is a Column Value/Family Datastore?
Values are stored within columns, consisting of a unique name, value and time stamp (to warn of stale).
What is a Graph Datastore?
Focusses on relationships between variables. Features networks of nodes and links.
What is a Key Value Datastore?
Values can be retrieved by knowing the key for which the value was stored. Simple to retrieve values once you know the key.
