什么是 DynamoDB？

DynamoDB 技能为开发者提供了一个全面的框架，使用专业级模式设计和操作 Amazon DynamoDB。它专注于解决 Serverless 生态系统中的常见 NoSQL 挑战，如热分区、低效扫描以及复杂的数据关系。

通过在 Openclaw Skills 中使用此技能，用户可以确保其数据库架构在性能和成本上都得到优化。它涵盖了从基础键设计到单表设计和事务完整性等高级概念，是云原生应用开发的必备工具。

下载入口:https://github.com/openclaw/skills/tree/main/skills/ivangdavila/dynamodb

安装与下载

1. ClawHub CLI

从源直接安装技能的最快方式。

2. 手动安装

将技能文件夹复制到以下位置之一

优先级：工作区 > 本地 > 内置

3. 提示词安装

将此提示词复制到 OpenClaw 即可自动安装。

DynamoDB 应用场景

• 设计在任何规模下都能保持稳定毫秒级延迟的可扩展后端。
• 使用单表设计模式将关系型数据模型迁移到 NoSQL。
• 通过优化读/写容量单位 (RCU/WCU) 来降低 AWS 运营成本。
• 使用生存时间 (TTL) 属性实现自动化的数据保留策略。
• 通过条件写入和事务确保分布式系统中的数据一致性。

1. 定义访问模式，以确定用于数据分布的最佳分区键 (PK) 和用于范围查询的排序键 (SK)。
2. 评估是否需要全局二级索引 (GSI) 作为替代搜索路径，以避免高昂的全表扫描。
3. 使用 FilterExpressions 实现查询操作，在保持高性能的同时精炼结果。
4. 将条件逻辑应用于写入操作，以处理乐观锁并防止数据覆盖。
5. 通过使用 LastEvaluatedKey 的递归分页逻辑管理大型数据集，以获取完整结果集。

DynamoDB 配置指南

要使用此技能，请确保已安装 AWS CLI 并配置了访问 DynamoDB 资源的适当权限。

# 验证 AWS CLI 安装
aws --version

# 配置您的 AWS 环境
aws configure

确保您的 IAM 策略拥有目标表的必要 dynamodb:GetItem、dynamodb:PutItem、dynamodb:Query 和 dynamodb:Scan 权限。

DynamoDB 数据架构与分类体系

该技能根据 DynamoDB 的严格结构限制和 Openclaw Skills 工作流的最佳实践管理数据：

name: DynamoDB
description: Design DynamoDB tables and write efficient queries avoiding common NoSQL pitfalls.
metadata: {"clawdbot":{"emoji":"?","requires":{"anyBins":["aws"]},"os":["linux","darwin","win32"]}}

Key Design

• Partition key determines data distribution—high-cardinality keys spread load evenly
• Hot partition = one key gets all traffic—use composite keys or add random suffix
• Sort key enables range queries within partition—design for access patterns
• Can't change keys after creation—model all access patterns before creating table

Query vs Scan

• Query uses partition key + optional sort key—O(items in partition), always prefer
• Scan reads entire table—expensive, slow, avoids indexes; almost never correct
• "I need to filter by X" usually means missing GSI—add index, don't scan
• FilterExpression applies AFTER read—still consumes full read capacity

Global Secondary Indexes

• GSI = different partition/sort key—enables alternate access patterns
• GSI is eventually consistent—writes propagate with slight delay
• GSI consumes separate capacity—provision or pay for each GSI independently
• Sparse index trick: only items with attribute appear in GSI

Single-Table Design

• One table for multiple entity types—prefix partition key: USER#123, ORDER#456
• Overloaded sort key: METADATA, ORDER#2024-01-15, ITEM#abc
• Query returns mixed types—filter client-side or use begins_with
• Not always right—start with access patterns, not doctrine

Pagination

• Results capped at 1MB per request—must handle pagination
• LastEvaluatedKey in response means more pages—pass as ExclusiveStartKey
• Loop until LastEvaluatedKey is absent—common mistake: assume one call gets all
• Limit limits evaluated items, not returned—still need pagination logic

Consistency

• Reads are eventually consistent by default—may return stale data
• ConsistentRead: true for strong consistency—costs 2x read capacity
• GSI reads always eventually consistent—no strong consistency option
• Write-then-read needs consistent read or retry—eventual consistency bites here

Conditional Writes

• ConditionExpression for optimistic locking—fails if condition false
• Prevent overwrites: attribute_not_exists(pk)
• Version check: version = :expected then increment
• ConditionCheckFailedException = retry with fresh data, don't just fail

Batch Operations

• BatchWriteItem is NOT atomic—partial success possible, check UnprocessedItems
• Retry unprocessed with exponential backoff—built into AWS SDK
• Max 25 items per batch, 16MB total—split larger batches
• No conditional writes in batch—use TransactWriteItems for atomicity

Transactions

• TransactWriteItems for atomic multi-item writes—all or nothing
• Max 100 items per transaction, 4MB total
• TransactGetItems for consistent multi-read—snapshot isolation
• 2x cost of normal operations—use only when atomicity required

TTL

• Enable TTL on timestamp attribute—DynamoDB deletes expired items automatically
• Deletion is background process—items may persist hours after expiration
• TTL value is Unix epoch seconds—milliseconds silently fails
• Filter attribute_exists(ttl) AND ttl > :now for queries if needed

Capacity

• On-demand: pay per request, auto-scales—good for unpredictable traffic
• Provisioned: set RCU/WCU, cheaper at scale—needs capacity planning
• Provisioned with auto-scaling for predictable patterns—set min/max/target
• ProvisionedThroughputExceededException = throttled—back off and retry

Limits

• Item size max 400KB—store large objects in S3, reference in DynamoDB
• Partition throughput: 3000 RCU, 1000 WCU—spread across partitions
• Query/Scan returns max 1MB—pagination required for more
• Attribute name max 64KB total per item—don't use long attribute names