When Scan is acceptable in DynamoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Scan operation in DynamoDB?

A Scan operation reads every item in a DynamoDB table and returns all data attributes by default. It examines the entire table.

beginner

When is it acceptable to use Scan in DynamoDB?

Scan is acceptable when the table is small, or when you need to retrieve all items without filtering by keys, or during development/testing.

beginner

Why should Scan be avoided on large DynamoDB tables?

Because Scan reads every item, it can be slow and expensive on large tables, consuming a lot of read capacity and increasing latency.

intermediate

How can you reduce the cost of a Scan operation?

You can reduce cost by using FilterExpression to return fewer items, paginating results, or using parallel scans to speed up the process.

beginner

What is a better alternative to Scan when you know the partition key?

Using Query is better because it retrieves items based on the partition key efficiently without scanning the whole table.

When is it acceptable to use a Scan operation in DynamoDB?

A When you know the partition key

B When the table is small or you need all items

C When you want to update a single item

D When you want to delete an item

Scan is acceptable when the table is small or when you need to retrieve all items without filtering by keys.

What is a downside of using Scan on large tables?

A It is very fast

B It updates items automatically

C It consumes a lot of read capacity and is slow

D It only returns one item

Scan reads every item, which can be slow and costly on large tables.

Which DynamoDB operation is more efficient than Scan when you know the partition key?

A PutItem

B DeleteItem

C UpdateItem

D Query

Query retrieves items based on the partition key efficiently without scanning the whole table.

How can you reduce the cost of a Scan operation?

A Use FilterExpression and pagination

B Scan the table multiple times

C Avoid using indexes

D Use Scan only on large tables

Using FilterExpression and pagination reduces the amount of data returned and cost.

Which scenario is NOT a good use case for Scan?

A Large tables with known keys

B Development and testing

C Small tables

D Retrieving all items without filters

Scan should be avoided on large tables when keys are known; Query is better.

Explain when it is acceptable to use a Scan operation in DynamoDB and why.

Think about table size and use cases where filtering by keys is not needed.

Describe the differences between Scan and Query in DynamoDB and when to prefer each.

Focus on efficiency and use cases.