Composite primary key in DynamoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a composite primary key in DynamoDB?

A composite primary key in DynamoDB is made of two parts: a partition key and a sort key. Together, they uniquely identify each item in a table.

beginner

Why use a composite primary key instead of a simple primary key?

Using a composite primary key lets you store multiple related items with the same partition key but different sort keys. This helps organize data and query it efficiently.

beginner

In DynamoDB, what does the partition key do in a composite primary key?

The partition key decides which partition (storage unit) the data goes to. It groups items together for fast access.

beginner

What role does the sort key play in a composite primary key?

The sort key orders items within the same partition key. It lets you store and query multiple items with the same partition key but different sort keys.

intermediate

How does a composite primary key help with querying data in DynamoDB?

It allows you to find all items with the same partition key and filter or sort them by the sort key. This makes queries more flexible and efficient.

What two parts make up a composite primary key in DynamoDB?

A Index key and sort key

B Primary key and foreign key

C Hash key and range key

D Partition key and sort key

A composite primary key consists of a partition key and a sort key. (Note: Hash key and range key are older terms for partition and sort keys.)

What does the partition key determine in DynamoDB?

A Which partition stores the item

B The total number of items in the table

C The order of items within a partition

D The size of the item

The partition key decides which partition stores the item, helping distribute data.

Can two items in DynamoDB have the same partition key but different sort keys?

A Yes, if they have different sort keys

B No, partition keys must be unique

C Yes, but only if they are in different tables

D No, both keys must be unique together

Items can share the same partition key if their sort keys differ, allowing multiple related items.

What advantage does a composite primary key provide when querying data?

A It allows filtering by partition key only

B It speeds up writes but not reads

C It enables sorting and filtering within a partition

D It removes the need for indexes

The sort key lets you sort and filter items within the same partition key.

Which of these is NOT true about composite primary keys in DynamoDB?

A They uniquely identify each item in the table

B They allow multiple items with the same partition and sort key

C They consist of a partition key and a sort key

D They help organize data for efficient queries

Items cannot have the same partition key and sort key combination; that would not be unique.

Explain what a composite primary key is in DynamoDB and why it is useful.

Think about how two keys work together to organize and find data.

Describe how the partition key and sort key work together in a composite primary key.

Consider their roles in storing and retrieving data.