Skip to content

Create a Local Secondary Index

Create a Local Secondary Index sits at the heart of local secondary indexes in DynamoDB. This guide walks through the concept step by step, with examples, a cheatsheet, and common mistakes to avoid.

Create a Local Secondary Index Overview

Create a Local Secondary Index is a building block you will reach for often in DynamoDB. It keeps related logic together and makes your intent obvious to reviewers and future maintainers.

When you learn create a local secondary index properly, you avoid the guesswork that leads to bugs and rework. The example below shows the shape you will use in most real DynamoDB projects.

import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
import { DynamoDBDocumentClient, PutCommand } from '@aws-sdk/lib-dynamodb';

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

await docClient.send(new PutCommand({
  TableName: 'Orders',
  Item: { pk: 'ORDER#123', sk: 'META', total: 42, status: 'NEW' },
  ConditionExpression: 'attribute_not_exists(pk)',
}));

PutCommand writes an item; the condition expression prevents overwriting an existing one.

Create a Local Secondary Index Example

import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
import { DynamoDBDocumentClient } from '@aws-sdk/lib-dynamodb';

const docClient = DynamoDBDocumentClient.from(new DynamoDBClient({}));
// docClient.send(new PutCommand(...)) etc.
  • Start from a minimal Create a Local Secondary Index example and grow it only as needed.
  • Keep configuration explicit so Create a Local Secondary Index behaves the same in every environment.
  • Name things clearly so teammates understand your Create a Local Secondary Index at a glance.
  • Add tests around Create a Local Secondary Index early to lock in expected behaviour.

Amazon DynamoDB Cheatsheet

Handy DynamoDB (AWS SDK v3) reference related to create a local secondary index.

Operation Command Purpose
Create/replace PutCommand Write an item
Read one GetCommand Fetch by primary key
Update UpdateCommand Modify attributes
Delete DeleteCommand Remove an item
Query QueryCommand Efficient key-based read
Scan ScanCommand Full-table read (avoid)
Transaction TransactWriteCommand Atomic multi-item writes

How Create a Local Secondary Index Works in DynamoDB

Create a Local Secondary Index builds on DynamoDB's key-value and document model, where every item lives in a partition chosen by its partition key and is optionally ordered by a sort key.

PutCommand writes an item; the condition expression prevents overwriting an existing one.

  • Design access patterns first, then model keys around them.
  • Prefer Query over Scan for predictable performance.
  • Use expressions to read and write only what you need.
  • Keep items small and avoid hot partitions.

Practical Guidance for Create a Local Secondary Index

In production, create a local secondary index should be cost-aware and resilient. Right-size capacity, handle throttling with retries, and lean on indexes to support your query patterns.

Concern Recommendation
Performance Query by key; avoid table scans
Cost Use on-demand or right-sized provisioned capacity
Modeling Design for known access patterns
Reliability Retry throttled requests with backoff

Common Mistakes

  • Skipping error handling and edge cases when wiring up create a local secondary index.
  • Leaving create a local secondary index untested, so regressions slip into production.
  • Over-engineering create a local secondary index before you actually need the extra flexibility.
  • Ignoring documentation, which makes create a local secondary index hard for the next developer to change.

Key Takeaways

  • Create a Local Secondary Index is a core part of working effectively with DynamoDB.
  • Start small and keep create a local secondary index focused on a single responsibility.
  • Apply consistent patterns so create a local secondary index scales across your project.
  • Test and document create a local secondary index to keep it maintainable over time.

Pro Tip

Pair create a local secondary index with automated tests from day one. It is far cheaper to catch DynamoDB regressions in CI than in production.

You now understand create a local secondary index in DynamoDB and how to apply it in real projects. Next, continue with Query a Local Secondary Index to keep building your skills.