NoSQL Final Exam Questions With Verified
And Updated Answers
What factors let to the emergence of NoSQL databases? - answer✔1) Impedance mismatch:
differences between relational models and data structures used by applications that interact
with databases
2) Web services: shift to web services (using HTTP) in early 2000's, need more flexibility in data
structure
3) Big data: rapid data expansion -- either scale up or scale out
4) Clustered computing: RDBMS not optimized for clusters, ACID transactions degrade
performance at scale
How do NoSQL data models address impedance mismatch? - answer✔Eliminate the need for
object-relational mapping, simplify database interactions, and there is less code to write /
maintain
Store data the way you want to retrieve it
Explain horizontal vs. vertical scaling - answer✔Vertical scaling (scaling up): bigger machines,
more expensive and ultimately reaches upper limits
Horizontal scaling (scaling out): add more machines to cluster, cheaper at scale and more
resilient and reliable
General defining characteristics of NoSQL - answer✔1) Do not use relational model
ALL RIGHTS RESERVED.
2) Do not use SQL as query language
3) "schemaless"
4) Mostly designed for clusters
5) Usually open-source
6) specialized for specific use cases
7) Developed in early 2000's and on
What is aggregate orientation? - answer✔Related objects are grouped together and treated as
one unit
We communicate with the database in terms of aggregates
Clusters use aggregates as units of data distribution
What are the benefits of a dynamic schema? - answer✔Different records can have different
structures, not as rigid
In RDBMS, we must define structure beforehand and take database offline to make changes
State the CAP theorem - answer✔A distributed computer system cannot simultaneously
provide (1) consistency, (2) availability, and (3) partition tolerance
Define consistency - answer✔The client perceives that a set of operations has occurred all at
once
All clients see the same data
"Atomicity" and "Consistency" from ACID
Define availability - answer✔Every request received by a non-failing node must result in a
response
Every request receives a response about whether it was successful or failed
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