Hash-based sharding in MongoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is hash-based sharding in MongoDB?

Hash-based sharding is a method where MongoDB uses a hash of the shard key's value to distribute data evenly across shards. This helps balance the load by spreading documents uniformly.

beginner

Why does MongoDB use a hash of the shard key for sharding?

Using a hash of the shard key ensures data is spread evenly across shards, preventing hotspots where one shard gets too much data or traffic.

intermediate

How does hash-based sharding differ from range-based sharding?

Hash-based sharding distributes data by hashing the shard key, creating a uniform spread. Range-based sharding divides data into ranges of shard key values, which can lead to uneven distribution if data is skewed.

beginner

What is a shard key in MongoDB's hash-based sharding?

A shard key is a field or set of fields in a document that MongoDB uses to determine how to distribute data across shards. In hash-based sharding, the hash of this key decides the shard placement.

intermediate

What is a potential downside of hash-based sharding?

Hash-based sharding can make range queries less efficient because data is spread randomly, so related data might be on different shards.

What does MongoDB use to decide where to place data in hash-based sharding?

A The range of shard key values

B The document's creation date

C The size of the document

D A hash of the shard key value

MongoDB hashes the shard key value to distribute data evenly across shards.

Which is a benefit of hash-based sharding?

A Data always stored on a single shard

B Faster range queries

C Even data distribution across shards

D Data stored in sorted order

Hash-based sharding spreads data evenly to avoid hotspots.

What is a shard key in MongoDB?

A A password for database access

B A field used to split data across shards

C The name of the database

D The size limit of a shard

The shard key determines how MongoDB distributes data among shards.

What is a downside of hash-based sharding?

A Range queries can be slower

B Data is not evenly distributed

C It only works with numeric keys

D It requires manual data balancing

Because data is spread randomly, range queries may need to check multiple shards.

How does hash-based sharding compare to range-based sharding?

A Hash-based spreads data evenly; range-based can cause uneven distribution

B Range-based always spreads data evenly; hash-based does not

C Both methods store data in sorted order

D Hash-based sharding is slower in all cases

Hash-based sharding uses hashing to balance data, while range-based can lead to uneven data if values cluster.

Explain how hash-based sharding works in MongoDB and why it is used.

Think about how hashing helps spread data evenly.

Describe one advantage and one disadvantage of using hash-based sharding.

Consider how data is spread and how queries might be affected.