DynamoDB Streams overview in AWS - Step-by-Step Execution

Process Flow - DynamoDB Streams overview

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 consumer reads records

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Consumer processes changes

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End

When data changes in a DynamoDB table, Streams capture these changes as records. A consumer reads and processes these records to react to the changes.

Execution Sample

AWS

1. Write item to DynamoDB table
2. DynamoDB Streams captures this write
3. Stream record created with change details
4. Consumer reads stream record
5. Consumer processes the change

This sequence shows how a data write triggers a stream record that a consumer reads and processes.

Process Table

Step	Action	Stream Record Created?	Consumer Reads?	Consumer Processes?
1	Write item to DynamoDB table	No	No	No
2	DynamoDB Streams captures change	Yes	No	No
3	Stream record available	Yes	No	No
4	Consumer reads stream record	Yes	Yes	No
5	Consumer processes the change	Yes	Yes	Yes
6	No new changes	No	No	No

💡 No new changes in DynamoDB, so no new stream records or processing

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 4	After Step 5	Final
DynamoDB Table Data	Empty	Item added	Item added	Item added	Item added	Item added
Stream Records	Empty	Empty	One record created	One record read	One record processed	One record processed
Consumer State	Idle	Idle	Idle	Reading	Processing	Idle

Key Moments - 3 Insights

Why doesn't the consumer process anything immediately after the item is written?

Because the stream record is created only after the write completes (see Step 2 and 3 in execution_table). The consumer reads and processes only after the record exists.

Can the consumer read stream records before they are created?

No, the consumer can only read records after DynamoDB Streams captures the change and creates the record (Step 3).

What happens if no data changes occur in the table?

No new stream records are created, so the consumer has nothing to read or process (Step 6).

Visual Quiz - 3 Questions

Look at the execution_table, at which step does the stream record get created?

A Step 1

B Step 2

C Step 4

D Step 5

💡 Hint

Check the 'Stream Record Created?' column in execution_table

According to variable_tracker, what is the consumer state after Step 4?

A Reading

B Processing

C Idle

D Waiting

💡 Hint

Look at the 'Consumer State' row and the 'After Step 4' column

If no new data changes happen, what happens to the stream records and consumer processing?

A New stream records are created and processed

B Consumer processes old records repeatedly

C No new stream records, consumer remains idle

D Stream records are deleted automatically

💡 Hint

Refer to Step 6 in execution_table and final states in variable_tracker

Concept Snapshot

DynamoDB Streams capture table data changes as records.
Each change (insert, update, delete) creates a stream record.
Consumers read these records to react to changes.
Stream records appear shortly after data changes.
No changes mean no new stream records or processing.

Full Transcript

DynamoDB Streams work by capturing changes made to a DynamoDB table. When you write, update, or delete an item, the stream records this change. These records are then available for a consumer application to read and process. The flow starts with a data change, followed by stream record creation, then the consumer reads and processes the record. If no changes happen, no new stream records are created, and the consumer remains idle. This process helps applications react to data changes in near real-time.