Introduction to NoSQL Databases. Exam
Questions With Verified And Updated
Answers
What is NOSQL? - answer✔NoSQL is a class of database management system identified by its
non-adherence to the widely used relational database management system (RDBMS) model
with its structured query language (SQL).
NOSQL has evolved to mean "Not Only" SQL
NOSQL has become prominent with the advent of web scale data and systems created by
Google, Facebook, Amazon, Twitter and others to manage data for which SQL was not the best
fit.
Why NoSQL databases? - answer✔-The (exponential growth) of the volume of data generated
by users and systems
-The (increasing interdependency) and complexity of data, accelerated by the Internet, Web
2.0, social networks
NoSQL databases are useful when working with a huge quantity of data and the data's nature
does not require a relational model for the data structure
Advantages of NoSQL Databases - answer✔Massive write performance.
Fast key value look ups.
Flexible schema and data types.
No single point of failure.
Fast prototyping and development.
Out of the box scalability (particularly Horizontal scalability).
Vertical scalability - answer✔Also called scaling up
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Increasing server capacity.
Adding more CPU, RAM.
Managing is hard.
Possible down times
Horizontal scalability - answer✔-Scale-out, Adding servers to existing system with little effort,
aka Elastically scalable
-Bugs, hardware errors, things fail all the time.
-It should become cheaper. Cost efficiency.
-Shared nothing
-Use of commodity/cheap hardware
-Heterogeneous systems
NoSQL characteristics - answer✔-Does not use SQL as its query language
NoSQL databases are not primarily built on tables, and generally do not use SQL for data
manipulation (but some have SQL like interfaces
-May not give full ACID guarantees
Usually only eventual consistency is guaranteed or transactions limited to single data items
-Distributed, fault-tolerant architecture
Data are partitioned and held on large number of servers, and is replicated among these
machines: horizontal scaling
RDBMS: Pros and Cons - answer✔Pros:
Many programmers are already familiar with it.
Transactions and ACID make development easy.
Lots of tools to use.
Rigorous Design (Schema)
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