Patterns for using DynamoDB, AWS’s managed NoSQL database, including one-table designs, composite keys, indexes, version checks, and batch operations. They also cover querying, scanning, expiration, and the AWS SDK’s document client.

Designing partition and sort keys, adding indexes for common lookups, preventing simultaneous updates from overwriting each other, handling retries, and setting item expiration.

They help avoid slow or expensive scans, lost updates, unhandled batch items, and database designs that do not match how the application reads data.

dynamodb — Cursor rule by GoranErhartic

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add rules/goranerhartic/cursor-development-rules/dynamodb

Clone the repo

git clone --depth 1 https://github.com/GoranErhartic/cursor-development-rules

Made for: Cursor.

Per session 41 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.

When invoked 517 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5	$0.00041	$0.00517
Opus 5	$0.00020	$0.00259
Sonnet 5	$0.00008	$0.00103
Haiku 4.5	$0.00004	$0.00052

Measured 2d ago against content hash bee147ccbbc6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

dynamodb scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/languages/aws-lambda/dynamodb.mdc · 47 lines

What it actually says

DynamoDB Patterns

Overview

Use single-table design with overloaded PK/SK and GSIs. Use AWS SDK v3: @aws-sdk/client-dynamodb, @aws-sdk/lib-dynamodb (DocumentClient).

Client

DynamoDBDocumentClient.from(DynamoDBClient); singleton; marshallOptions: { removeUndefinedValues: true }; avoid convertEmptyValues

Key Design

PK/SK: Composite keys (e.g. PROPERTY#<id>, LISTING#<id>); use METADATA or similar for single-item entity record
GSI: Overload GSI1PK/GSI1SK for access patterns (e.g. by owner, by agent, by status+time); project only needed attributes if desired
Entity type: Include entityType (or use PK/SK prefix) for filtering

Operations

GetItem: By PK + SK
PutItem: Use conditional expression for optimistic locking: version = :currentVersion; increment version on update
Query: By PK (required); optional SK condition (begins_with, between, =); filter expression for post-query filter
BatchGetItem: Up to 100 items; handle UnprocessedKeys and retry
BatchWriteItem: Put/Delete; handle UnprocessedItems; do not exceed 25 items per request
Scan: Avoid or limit; use parallel scan only when necessary with segment/totalSegments

Optimistic Locking

Add version (number) to entities; on update set ConditionExpression: 'version = :v', :v = current; increment in update expression

TTL

Add ttl attribute (Unix timestamp); enable TTL on table to desired attribute

Conventions

Single table per service/domain; consistent key naming; always use condition for overwrite-sensitive writes; propagate correlationId in logs

Anti-Patterns

Multiple tables for same domain; scan without limit; ignoring UnprocessedKeys/UnprocessedItems; no version for concurrent updates

See also: dynamodb-streams.mdc, idempotency.mdc, ../../patterns/architecture.mdc

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2d ago First seen · 47 lines · 41 tokens per session scan A bee147ccbbc6

Subscribe to this mod's changes

dynamodb is a cursor rule published in the GitHub repository GoranErhartic/cursor-development-rules (19 stars, last pushed 6mo ago), licensed MIT. It adds 41 tokens to every session and 517 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Databases DevOps and cloud Documents

dynamodb

Getting it into your agent

What it costs to keep this loaded

Grade A, and why

Nothing flagged

What it actually says

DynamoDB Patterns

Overview

Client

Key Design

Operations

Optimistic Locking

TTL

Conventions

Anti-Patterns

What this file has done since we first saw it

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