CLOUD / A CONCEPT NOTE
DynamoDB
serverless NoSQL database with single-digit millisecond latency
Overview · mechanism
pitfall · examples
01 / THE SHORT VERSION
The idea in a few sentences.
DynamoDB is a fully managed key-value and document database. You define a table with a primary key (partition key + optional sort key), and DynamoDB automatically distributes data across partitions. It scales horizontally — throughput is provisioned or on-demand. It's the backbone of countless serverless architectures at Amazon.
02 / FOLLOW THE MECHANISM
How dynamodb serves a query
Application
calls
GetItemwith a primary key:{ 'userId': 'user_abc123' }.DynamoDB
hashes the partition key to determine which partition (physical storage node) holds the data.
Partition
retrieves the item from SSD storage within the partition and returns it.
Consistency
by default, reads are eventually consistent (1s replication lag). Strongly consistent reads cost more but return the latest data.
04 / COMMAND NOTES
Read the command, then the result.
Inspect the flags and arguments before trying an example. Snippets can need local setup, replacement values, or resources in your own environment.
inspect table metadata, indexes, and capacity
aws dynamodb describe-table --table-name my-tablescan all items (expensive on large tables)
aws dynamodb scan --table-name my-table05 / CHECK YOURSELF
Could you explain DynamoDB to a teammate?
Try it out loud in two sentences: what it is, and the one detail that changes the picture. If you stall, the gap is the part to reread.
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