$ ls ./writing

AWS concepts, explained simply.

Practical breakdowns of AWS topics from core services to architecture patterns.

21 August 20267 min read

DynamoDB On-Demand does not mean unlimited: the four limits that still throttle you

On-Demand looks like infinite scale until it throttles. The initial 4,000 WCU ceiling, the 2× previous peak rule, the 40,000 table quota, and the per-partition limit you cannot raise at any price.

AWS
Serverless
DynamoDB
Scaling

AWS Cost and usage dashboard showing a 430% jump to $21.47, with CloudFront at $16.24 and Simple Queue Service at $0.09 in the August breakdown.

20 August 202612 min read

The nine cents that worried me: SQS empty receives, short polling and 135K wasted requests a day

A 430% AWS bill jump had an obvious culprit and an interesting one. The interesting one was nine cents of SQS charges from queues serving almost no messages. How SQS request pricing works, the metric that exposes it, and the two fixes.

AWS
Serverless
Cost optimisation
SQS