Databases & System Design•Part 3: NoSQL & Document Databases (MongoDB, DynamoDB) (26 - 40)
DynamoDB Partition Keys, Sort Keys & Hot Partitions:
In Simple Words:
- Partition Key (HASH): Determines which physical storage partition data goes to.
- Sort Key (RANGE): Orders items within the partition.
- Hot Partition: Occurs when access heavily hits a single key, exceeding per-partition limits (1,000 WCU or 3,000 RCU).
typescript
// AWS SDK v3 DynamoDB Query using Partition Key (PK) and Sort Key (SK):
import { DynamoDBClient, QueryCommand } from "@aws-sdk/client-dynamodb";
const command = new QueryCommand({
TableName: "AppTable",
KeyConditionExpression: "PK = :pk AND SK begins_with(:skPrefix)",
ExpressionAttributeValues: {
":pk": { S: "USER#101" },
":skPrefix": { S: "ORDER#" }
}
});