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DynamoDB Streams overview in AWS - Cheat Sheet & Quick Revision

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beginner
What is DynamoDB Streams?
DynamoDB Streams is a feature that captures changes made to items in a DynamoDB table and stores them as a time-ordered sequence of events.
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beginner
How long are records kept in DynamoDB Streams?
Records in DynamoDB Streams are kept for 24 hours before they expire and are removed.
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beginner
What types of data changes does DynamoDB Streams capture?
It captures item-level changes such as inserts, updates, and deletes.
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intermediate
What is a shard in DynamoDB Streams?
A shard is a container for a sequence of stream records. It helps organize and process the stream data in order.
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intermediate
How can you use DynamoDB Streams in an application?
You can use DynamoDB Streams to trigger AWS Lambda functions or replicate data to other systems, enabling real-time processing of table changes.
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What does DynamoDB Streams capture?
AUser login events
BNetwork traffic logs
CChanges to items in a DynamoDB table
DBackup snapshots
How long are records stored in DynamoDB Streams before they expire?
A30 days
B7 days
CIndefinitely
D24 hours
Which AWS service can be triggered by DynamoDB Streams for real-time processing?
AAWS Lambda
BAmazon S3
CAmazon EC2
DAWS CloudTrail
What is a shard in the context of DynamoDB Streams?
AA backup copy of the table
BA container for a sequence of stream records
CA type of database index
DA user permission level
Which of the following is NOT a use case for DynamoDB Streams?
AStoring large files
BTriggering workflows on data changes
CReal-time data replication
DAuditing item-level changes
Explain what DynamoDB Streams is and how it helps in managing data changes.
Think about how changes in a database can be tracked and used immediately.
You got /4 concepts.
    Describe how DynamoDB Streams integrates with AWS Lambda and why this is useful.
    Consider how automatic reactions to data changes can improve applications.
    You got /4 concepts.

      Practice

      (1/5)
      1. What is the main purpose of DynamoDB Streams?
      easy
      A. To store backups of DynamoDB tables permanently
      B. To encrypt data stored in DynamoDB tables
      C. To increase the read capacity of a DynamoDB table
      D. To track and react to data changes in real time

      Solution

      1. Step 1: Understand DynamoDB Streams function

        DynamoDB Streams capture data changes like inserts, updates, and deletes in real time.

      2. Step 2: Compare options with Streams purpose

        Only To track and react to data changes in real time correctly describes tracking and reacting to data changes. Other options describe unrelated features.

      3. Final Answer:

        To track and react to data changes in real time -> Option D

      4. Quick Check:

        DynamoDB Streams = Track data changes [OK]
      Hint: Streams capture table changes instantly for reaction [OK]
      Common Mistakes:
      • Confusing Streams with backup or encryption features
      • Thinking Streams increase read capacity
      • Assuming Streams store data permanently
      2. Which setting must be enabled to start using DynamoDB Streams on a table?
      easy
      A. EncryptionEnabled set to true
      B. BackupEnabled set to true
      C. StreamEnabled set to true
      D. AutoScalingEnabled set to true

      Solution

      1. Step 1: Identify the configuration for enabling Streams

        To use DynamoDB Streams, the table must have StreamEnabled set to true.

      2. Step 2: Eliminate unrelated settings

        BackupEnabled, EncryptionEnabled, and AutoScalingEnabled do not enable Streams.

      3. Final Answer:

        StreamEnabled set to true -> Option C

      4. Quick Check:

        Enable Streams = StreamEnabled true [OK]
      Hint: Enable Streams by setting StreamEnabled true [OK]
      Common Mistakes:
      • Confusing Streams with backups or encryption
      • Assuming AutoScaling enables Streams
      • Forgetting to enable Streams explicitly
      3. Given a DynamoDB Stream with StreamViewType set to NEW_AND_OLD_IMAGES, what data will the stream record for each change?
      medium
      A. Only the new item image after the change
      B. Both the new and old item images
      C. Only the keys of the changed items
      D. Only the old item image before the change

      Solution

      1. Step 1: Understand StreamViewType NEW_AND_OLD_IMAGES meaning

        This setting records both the item before and after the change.

      2. Step 2: Compare options with StreamViewType behavior

        Only Both the new and old item images matches the behavior of capturing both new and old images.

      3. Final Answer:

        Both the new and old item images -> Option B

      4. Quick Check:

        NEW_AND_OLD_IMAGES = new + old data [OK]
      Hint: NEW_AND_OLD_IMAGES means capture before and after data [OK]
      Common Mistakes:
      • Choosing only new or only old images
      • Confusing keys only with full images
      • Not knowing StreamViewType options
      4. A developer enabled DynamoDB Streams but does not see any stream records after table updates. What is the most likely cause?
      medium
      A. StreamEnabled is false on the table
      B. StreamViewType is set to KEYS_ONLY
      C. Stream retention period is set to 7 days
      D. The table has no primary key defined

      Solution

      1. Step 1: Check if Streams are enabled

        If StreamEnabled is false, no stream records are generated regardless of updates.

      2. Step 2: Evaluate other options

        KEYS_ONLY still produces records; retention period (24-168 hours) does not prevent seeing recent records; tables require primary keys but that doesn't stop streams if enabled.

      3. Final Answer:

        StreamEnabled is false on the table -> Option A

      4. Quick Check:

        No records = Streams not enabled [OK]
      Hint: Streams must be enabled to see records [OK]
      Common Mistakes:
      • Assuming KEYS_ONLY disables records
      • Thinking retention period prevents seeing records
      • Ignoring StreamEnabled setting
      5. You want to trigger a Lambda function whenever an item is updated in your DynamoDB table to process both the old and new item images. Which DynamoDB Streams configuration and setup is required?
      hard
      A. Enable Streams with StreamViewType NEW_AND_OLD_IMAGES and configure Lambda trigger on the stream
      B. Enable Streams with StreamViewType KEYS_ONLY and configure Lambda trigger on the table
      C. Enable Streams with StreamViewType NEW_IMAGE and configure Lambda trigger on the stream
      D. Enable Streams with StreamViewType OLD_IMAGE and configure Lambda trigger on the table

      Solution

      1. Step 1: Choose StreamViewType for updates

        To capture both before and after update data, use NEW_AND_OLD_IMAGES.

      2. Step 2: Configure Lambda trigger on the DynamoDB Stream

        Lambda triggers must be set on the stream, not directly on the table.

      3. Final Answer:

        Enable Streams with StreamViewType NEW_AND_OLD_IMAGES and configure Lambda trigger on the stream -> Option A

      4. Quick Check:

        Lambda trigger on stream with NEW_AND_OLD_IMAGES [OK]
      Hint: Use NEW_AND_OLD_IMAGES and trigger Lambda on stream [OK]
      Common Mistakes:
      • Triggering Lambda directly on table instead of stream
      • Choosing KEYS_ONLY or OLD_IMAGE for update data
      • Not enabling Streams before Lambda trigger
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