DynamoDB Streams concept - Step-by-Step Execution

Concept Flow - DynamoDB Streams concept

Data change in DynamoDB table

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DynamoDB Streams captures change

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Stream records created

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Stream consumers read records

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Process or react to changes

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Done

When data changes in a DynamoDB table, DynamoDB Streams captures these changes as records. Consumers then read these records to process or react to the changes.

Execution Sample

DynamoDB

1. Insert item into DynamoDB table
2. DynamoDB Streams captures INSERT event
3. Stream record created with new item data
4. Consumer reads stream record
5. Consumer processes the new item

This example shows how inserting an item triggers a stream record that a consumer reads and processes.

Execution Table

Step	Action	Stream Record Created?	Record Content	Consumer Action
1	Insert item into table	Yes	INSERT event with new item data	No action yet
2	Update item in table	Yes	MODIFY event with old and new data	No action yet
3	Delete item from table	Yes	REMOVE event with old item data	No action yet
4	Consumer reads first stream record	No	N/A	Processes INSERT event data
5	Consumer reads second stream record	No	N/A	Processes MODIFY event data
6	Consumer reads third stream record	No	N/A	Processes REMOVE event data
7	No more records	No	N/A	Consumer waits for new records

💡 All stream records processed; consumer waits for new changes.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6	Final
Stream Records Queue	Empty	INSERT record added	MODIFY record added	REMOVE record added	INSERT record removed	MODIFY record removed	REMOVE record removed	Empty

Key Moments - 3 Insights

Why does a stream record appear after each data change?

Because DynamoDB Streams captures every data modification (insert, update, delete) as a record, as shown in execution_table rows 1-3.

Does the consumer create stream records?

No, the consumer only reads and processes existing stream records created by DynamoDB Streams, as seen in execution_table rows 4-6.

What happens when there are no new changes in the table?

The consumer waits for new stream records since none are created without data changes, shown in execution_table row 7.

Visual Quiz - 3 Questions

Look at the execution_table, what type of event is recorded at Step 2?

A INSERT event

B MODIFY event

C REMOVE event

D No event

💡 Hint

Check the 'Stream Record Created?' and 'Record Content' columns at Step 2.

At which step does the consumer process the REMOVE event?

A Step 6

B Step 4

C Step 3

D Step 7

💡 Hint

Look at the 'Consumer Action' column for processing REMOVE event.

If no data changes happen, what will the stream records queue state be?

A Contains MODIFY records

B Contains INSERT records

C Empty

D Contains REMOVE records

💡 Hint

Refer to variable_tracker final state and execution_table Step 7.

Concept Snapshot

DynamoDB Streams capture table data changes as records.
Each INSERT, MODIFY, or REMOVE creates a stream record.
Consumers read these records to react to changes.
Stream records queue holds changes until processed.
No data change means no new stream records.

Full Transcript

DynamoDB Streams work by capturing every change made to a DynamoDB table. When you insert, update, or delete an item, a stream record is created that describes this change. These records are stored in a queue. Consumers then read these records one by one to process or react to the changes. If no changes happen, no new stream records are created, and consumers wait for new data. This flow ensures you can track and respond to all data changes in your table.