Query by partition key in DynamoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a partition key in DynamoDB?

A partition key is the primary key attribute that DynamoDB uses to distribute data across partitions. It uniquely identifies items within a table's partition.

beginner

How do you query items by partition key in DynamoDB?

You use the Query operation specifying the partition key value. This returns all items with that partition key efficiently.

intermediate

Why is Query by partition key faster than Scan in DynamoDB?

Query uses the partition key to directly find items, so it reads only relevant data. Scan reads the entire table, which is slower and more costly.

beginner

Can you query DynamoDB without specifying a partition key?

No, Query requires a partition key value. Without it, you must use Scan, which reads the whole table.

intermediate

What is the syntax to query a DynamoDB table by partition key using AWS CLI?

aws dynamodb query --table-name YourTableName --key-condition-expression "PartitionKeyName = :pkval" --expression-attribute-values '{":pkval":{"S":"YourKeyValue"}}'

What must you always provide when using the Query operation in DynamoDB?

A Index name only

B Sort key value

C Partition key value

D Table name only

Query requires the partition key value to find matching items.

Which operation reads the entire DynamoDB table?

A Query

B Scan

C GetItem

D UpdateItem

Scan reads every item in the table, unlike Query which uses the partition key.

What does the Query operation return when multiple items share the same partition key?

A Only one item

B An error

C No items

D All items with that partition key

Query returns all items that have the specified partition key.

Which of these is NOT required for a Query by partition key?

A Full table scan

B Sort key value (if table has one)

C Table name

D Partition key value

Query does not perform a full table scan; it uses the partition key to find items.

What is the main benefit of querying by partition key?

A Faster and cheaper data retrieval

B Retrieves all table data

C Updates multiple items

D Deletes items automatically

Querying by partition key is efficient and cost-effective because it targets specific data.

Explain how querying by partition key works in DynamoDB and why it is efficient.

Think about how DynamoDB organizes data and how Query uses that.

Describe the difference between Query and Scan operations in DynamoDB.

Focus on how much data each operation reads.