ETL Pipeline Review
Phase 1: Architecture Assessment
- Map the pipeline architecture
- Data sources and ingestion methods
- Transformation layers and logic
- Target data stores and schemas
- Orchestration and scheduling
- Dependencies between pipelines
- Data volume and processing time
- Document pipeline SLAs and requirements
- Identify single points of failure
Pipeline Architecture Summary
| Component | Technology | Input | Output | Volume | SLA |
|---|---|---|---|---|---|
| Ingestion | source | raw | GB/day | ||
| Transform | raw | cleaned | GB/day | ||
| Load | cleaned | warehouse | GB/day | ||
| Orchestration | N/A | N/A | N/A |
Phase 2: Reliability Review
- Assess pipeline reliability
- Idempotency: re-runs produce same result
- Exactly-once or at-least-once semantics
- Error handling and retry logic
- Dead letter queues for failed records
- Graceful handling of schema evolution
- Backfill capability for historical data
- Pipeline timeout configuration
- Alerting on pipeline failures
- Review failure history and patterns
Reliability Checklist
| Property | Implemented | Tested | Evidence |
|---|---|---|---|
| Idempotent re-runs | [ ] | [ ] | |
| Retry with backoff | [ ] | [ ] | |
| Dead letter handling | [ ] | [ ] | |
| Schema evolution | [ ] | [ ] | |
| Backfill support | [ ] | [ ] | |
| Timeout handling | [ ] | [ ] | |
| Partial failure recovery | [ ] | [ ] |
Phase 3: Performance Review
- Assess pipeline performance
- Processing time vs. SLA
- Resource utilization (CPU, memory, I/O)
- Partitioning strategy for parallelism
- Incremental processing (vs. full reload)
- Pushdown optimization (filter/aggregate at source)
- Data serialization format efficiency
- Shuffle and data skew issues (Spark)
- Connection pooling and resource management
- Identify performance bottlenecks
Performance Metrics
| Stage | Avg Duration | P95 Duration | SLA | Data Volume | Bottleneck |
|---|---|---|---|---|---|
| min | min | min | GB | CPU/IO/Network/Skew |
Phase 4: Data Quality Integration
- Assess data quality checks in pipeline
- Input validation (schema, null checks, ranges)
- Row count reconciliation (source vs. target)
- Business rule validation
- Duplicate detection
- Freshness checks
- Quality gates that halt pipeline on failure
- Data quality test framework (dbt tests, Great Expectations)
- Review data quality incident history
Phase 5: Testing & Maintainability
- Assess testing practices
- Unit tests for transformation logic
- Integration tests with test datasets
- End-to-end validation tests
- Test data management strategy
- CI/CD for pipeline code changes
- Assess maintainability
- Code organized and modular
- Documentation up to date
- Naming conventions consistent
- Configuration externalized (not hardcoded)
- Version control for all pipeline code
- Lineage tracking and metadata management
Phase 6: Recommendations
- Prioritize improvements by impact and effort
- Address reliability gaps first
- Optimize performance bottlenecks
- Enhance data quality checks
- Improve testing coverage
Review Summary
| Area | Score (1-5) | Key Finding | Recommendation | Priority |
|---|---|---|---|---|
| Architecture | ||||
| Reliability | ||||
| Performance | ||||
| Data Quality | ||||
| Testing | ||||
| Maintainability |
Counter-Rationalizations
| Shortcut | Counter | Why |
|---|---|---|
| "We can skip some steps for this case" | Adapt the workflow steps, don't skip them | Skipped steps are where incidents and oversights originate |
| "The user seems to already know what to do" | Complete all workflow phases with the user | The workflow catches blind spots that experience alone misses |
| "This is a minor case, full process is overkill" | Scale the process down, don't turn it off | Minor cases become major when unstructured; the process scales, not disappears |
| "I'll fill in the details later" | Complete each section before moving on | Deferred details are forgotten; real-time capture is more accurate |
| "The template output isn't necessary" | Always produce the structured output format | Structured output enables comparison, audit trails, and handoff to other teams |
Output Format
- Architecture Diagram: Pipeline flow with components and data stores
- Reliability Assessment: Failure modes and mitigation status
- Performance Report: Timing, bottlenecks, and optimization plan
- Quality Check Inventory: Current checks and gaps
- Improvement Plan: Prioritized recommendations
Action Items
- Document pipeline architecture and dependencies
- Implement missing reliability controls (idempotency, retries)
- Optimize top performance bottlenecks
- Add data quality checks at each pipeline stage
- Improve test coverage for transformations
- Set up pipeline monitoring and alerting
- Schedule quarterly pipeline review