构建 ETL 管道编排器

项目概述

本项目实现一个面向 batch data processing 的完整系统，核心要解决的问题是 running extract-transform-load stages with retries, ordering, and observability across large datasets。整体由 Stage graph、Task scheduler、Retry policy、Checkpoint store、Progress reporter 五个模块组成，每个模块单一职责、可独立测试，最后通过集成测试验证端到端正确性。设计上把 a stage that partially writes its output and then fails, leaving a dirty dataset that a retry doubles 作为第一类需求先行处理，而非事后再补。

架构与关键决策

数据模型为 a directed acyclic graph of stages each producing a dataset, scheduled with dependencies and checkpointed for resume。Stage graph 定义其余阶段共同依赖的数据形状并在边界处校验输入；Task scheduler 承载 batch data processing 的正确性逻辑；Retry policy 专门处理 a stage that partially writes its output and then fails, leaving a dirty dataset that a retry doubles，在失败路径上给出明确的拒绝、重试或降级策略；Checkpoint store 提供可观测性，每次操作输出带关联 id 的结构化事件；Progress reporter 在过载时按既定方式降级，避免过载演变为数据损坏。配置与代码分离，使风险变更可经 diff 审阅。

实施与测试

按五个阶段依次实现 Stage graph、Task scheduler、Retry policy、Checkpoint store、Progress reporter，每阶段配套聚焦单测。集成测试组合各模块并驱动真实 batch data processing 场景：先验证正常路径，再刻意触发 a stage that partially writes its output and then fails, leaving a dirty dataset that a retry doubles 并断言系统降级而非损坏。所有依赖均在进程内或被桩替换，用例在 CI 中确定可复现。

限制与后续

• 单区域设计，多区域复制超出范围。
• Stage graph 默认进程内，未水平共享。
• 无鉴权层，假定部署在强制身份的边缘之后。

代码示例

# setup for etl-pipeline-orchestrator
pnpm init
pnpm add fastify redis
pnpm add -D typescript tsx vitest

etl_pipeline_orchestrator/
├── src/index.ts
├── src/stage-graph.ts
├── src/task-scheduler.ts
├── tests/etl_pipeline_orchestrator.test.ts
└── package.json

// Stage graph: batch data processing core
export function stagegraph(input: StagegraphInput): StagegraphResult {
  // Build the stage graph that anchors batch data processing and defines the core data shape.
  return processStagegraph(input);
}

// Task scheduler — handles batch data processing Add the task scheduler so
export class Taskscheduler {
  constructor(private opts: TaskschedulerOptions) {}
  async run(ctx: Context): Promise<TaskschedulerOutput> {
    return this.execute(ctx);
  }
}

// Retry policy: batch data processing stage
export const retrypolicy = (next: Next) => async (req: Request) => {
  const out = await transform(req);
  return next(out);
};

// Checkpoint store for batch data processing
export async function checkpointstore(stream: AsyncIterable<Chunk>): Promise<Aggregate> {
  let acc = init();
  for await (const c of stream) acc = merge(acc, c);
  return acc;
}

// Progress reporter: batch data processing finalization
export function progressreporter(state: State): Result {
  validate(state);
  return finalize(state);
}

# run the batch data processing test suite
pnpm vitest run