Time Complexity: On-demand vs provisioned cost comparison
O(n)
0
0
On-demand vs provisioned cost comparison in DynamoDB - Performance Comparison
Understanding Time Complexity
When using DynamoDB, it's important to understand how costs grow as your data and traffic increase.
We want to see how the cost changes when using on-demand versus provisioned capacity modes.
Scenario Under Consideration
Analyze the cost behavior of these two capacity modes.
// On-demand mode: charges per request
// Provisioned mode: charges per capacity unit reserved
// Example usage:
// On-demand: pay for each read/write request
// Provisioned: pay fixed units, regardless of usage
This shows how DynamoDB charges differently based on your capacity mode choice.
Identify Repeating Operations
Look at what causes costs to repeat or grow.
- Primary operation: Number of read/write requests made to the database.
- How many times: Each request counts separately in on-demand mode; fixed in provisioned mode.
How Execution Grows With Input
Costs grow differently depending on mode and request volume.
| Request Volume (n) | On-demand Cost | Provisioned Cost |
|---|---|---|
| 10 | Low (pay per request) | Fixed (capacity units reserved) |
| 100 | Moderate (more requests, more cost) | Fixed (same reserved units) |
| 1000 | High (cost grows with requests) | Fixed or may need to increase capacity |
Pattern observation: On-demand cost grows linearly with requests; provisioned cost stays fixed until capacity is increased.
Final Time Complexity
Time Complexity: O(n) for on-demand mode cost growth
This means cost grows directly with the number of requests you make.
Common Mistake
[X] Wrong: "Provisioned mode cost grows with every request just like on-demand."
[OK] Correct: Provisioned mode charges a fixed rate for reserved capacity, not per request, so cost stays stable until you increase capacity.
Interview Connect
Understanding how costs scale with usage helps you design efficient and cost-effective DynamoDB solutions.
Self-Check
What if you switch from on-demand to provisioned mode but your request volume suddenly doubles? How would the cost behavior change?