Which of the following are true of NoSQL databases?
At a very basic level, they are similar to hash tables

What is database normalization?
The process of ensuring that a piece of data is not duplicated multiple times in a database

What is the role of denormalization in NoSQL database optimization?
Denormalization can be used to make reads faster by duplicating data and requiring fewer key-based lookups

Which of the following are ways to optimize reads for specific queries?
Grouping all data needed for a specific query and attaching it to a single key

How does a sharded counter work?
A counter is broken into multiple shards that are each stored under a different key. When the counter is read, each shard is fetched and the sum of the counter shards is returned. On writes, a counter shard is randomly chosen and incremented. Write parallelism is proportional to the number of shards.

What is the relationship between read and write optimization in NoSQL databases?
Many write optimization strategies require denormalization, which can increase read complexity
Many read optimization strategies require denormalization, which can increase write complexity

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Marcos Carvalho