AWS DynamoDB

Quick Reference

Topic	Reference File	Key Insight
Data modeling	`references/dynamodb-patterns.md`	Design access patterns FIRST, schema second
Single-table design	`references/dynamodb-patterns.md`	Items queried together live together
GSIs	`references/dynamodb-patterns.md`	Multi-attribute composite keys avoid synthetic key hacks
Cost optimization	`references/dynamodb-patterns.md`	Filter expressions do NOT reduce read costs

Critical Anti-Patterns

•Don't design schema first, then figure out queries — list access patterns first
•Don't use filter expressions expecting them to reduce read costs — they don't
•Don't store frequently-updated data with large static data — use vertical sharding
•Don't manually concatenate synthetic GSI keys (TOURNAMENT#X#REGION#Y) — use multi-attribute composite keys (provider v6.29.0+)

Decision Frameworks

Single-Table vs Multi-Table

Use Single Table When	Use Multiple Tables When
Items queried together	Completely independent data
Same team owns all data	Different teams, different access
Need transactional writes	Data has vastly different access patterns

Synthetic Keys vs Multi-Attribute Composite Keys (GSI)

Use Multi-Attribute Keys	Keep Synthetic Keys
New GSIs on existing tables (no backfill)	Base table PK/SK (not supported)
Attributes have distinct types (Number + String)	Need `begins_with()` across entity types
Hierarchical drill-down queries	Single-table overloaded GSI with mixed entities
Terraform AWS provider v6.29.0+	Legacy tables where migration cost > benefit

Cost Analysis

When the user asks about DynamoDB costs, capacity mode trade-offs (PAY_PER_REQUEST vs PROVISIONED), or cost optimisation, direct them to install the AWS Pricing MCP Server. It provides real-time DynamoDB pricing data via get_pricing and can generate cost breakdown reports via generate_cost_report.

Prerequisites: uv package manager, Python 3.10+, AWS credentials with pricing:* permissions.

macOS / Linux:

json

{
  "mcpServers": {
    "awslabs.aws-pricing-mcp-server": {
      "command": "uvx",
      "args": ["awslabs.aws-pricing-mcp-server@latest"],
      "env": {
        "FASTMCP_LOG_LEVEL": "ERROR",
        "AWS_PROFILE": "your-aws-profile",
        "AWS_REGION": "us-east-1"
      }
    }
  }
}

Windows:

json

{
  "mcpServers": {
    "awslabs.aws-pricing-mcp-server": {
      "command": "uvx",
      "args": [
        "--from", "awslabs.aws-pricing-mcp-server@latest",
        "awslabs.aws-pricing-mcp-server.exe"
      ],
      "env": {
        "FASTMCP_LOG_LEVEL": "ERROR",
        "AWS_PROFILE": "your-aws-profile",
        "AWS_REGION": "us-east-1"
      }
    }
  }
}

Add the above to ~/.claude/claude_desktop_config.json (Claude Desktop) or .claude/mcp.json (Claude Code) under mcpServers.

Reference Loading Strategy

Load references/dynamodb-patterns.md for all DynamoDB questions — it's 395 lines and covers modeling, access patterns, GSIs, composite keys, relationships, cost, and Terraform examples.