Who this is for
Data Engineers and platform builders who maintain pipelines, datasets, orchestration, and operational runbooks and want documentation that stays accurate as systems evolve.
Prerequisites
- Basic familiarity with your team’s code review process (pull requests or similar)
- Comfort writing Markdown-style docs and updating READMEs/runbooks
- Understanding of your data model (tables, columns, SLAs, lineage)
Why this matters
Out-of-date docs cause failed deployments, broken dashboards, and on-call stress. In real data engineering work you will:
- Ship schema changes that affect downstream teams
- Modify DAG schedules and SLAs
- Deprecate datasets or rename columns
- Hotfix jobs and adjust runbooks
Keeping docs updated prevents confusion, speeds onboarding, and reduces incidents.
Concept explained simply
Updated documentation is a habit plus a few guardrails. Treat docs like code: versioned, reviewed, and released with changes. When something changes in code, a corresponding doc change happens in the same PR or release.
Mental model
Think of your system as a contract between producers and consumers. Docs are the contract text. If the contract changes (schema, SLA, ownership), the contract must be reissued immediately. No reissue = broken trust.
Core practices (fast wins)
- Definition of Done includes docs updated (DoD: code merged only when docs are updated or explicitly N/A)
- Docs-as-code: store docs with the pipeline or dataset
- Change triggers: ship a doc update whenever any of these change:
- Table schema or column semantics
- DAG schedule, SLA/SLO, alerting
- Data quality checks or thresholds
- Ownership (team/on-call) or escalation path
- Dependencies/lineage or contracts
- Runbook procedures for failures
- Changelog: each dataset or pipeline keeps a human-readable changelog snippet per release
- Ownership and timestamps: each doc shows owner and last-reviewed date
Worked examples
Example 1: Renaming a column
Change: orders.total_price becomes orders.gross_amount.
- Docs to update: dataset README (column table), data dictionary entry, any example queries in docs
- Add deprecation note: mention old name and removal date
- Changelog line: “2026-02-12: total_price renamed to gross_amount; same calculation”
- Runbook: add temporary mapping tip for downstream fixes
Example 2: SLA change for a daily DAG
Change: Job now completes by 06:00 UTC instead of 04:00 UTC.
- Docs to update: pipeline README (Schedule & SLA section), consumer-impact note
- Alert policy doc: adjust alert window
- Changelog line: “SLA moved to 06:00 UTC; consumers adjust refresh expectations”
Example 3: Deprecating a dataset
Change: Replace legacy_events with events_v2.
- Docs to update: legacy dataset doc gets a bold deprecation banner with EOL date
- New dataset doc: includes migration guide (field mapping)
- Changelog lines on both datasets
- Runbook: add note for on-call on how to respond to legacy failures during wind-down
Step-by-step: Make updates part of delivery
- Before merging: add a “Docs impact” checklist to PR template
- Create/modify doc files in the same PR: README, schema table, runbook, changelog
- Tag owners for review: code reviewer checks docs updated, not just code
- On merge: ensure version/release notes include doc changes
- Weekly: 15-minute doc health scan (spot stale timestamps, missing owners)
Copy-paste PR checklist
- [ ] Docs impact reviewed
- [ ] Dataset fields updated (added/removed/renamed/semantics)
- [ ] Schedule/SLA and alerting updated
- [ ] Runbook steps updated
- [ ] Changelog entry added
- [ ] Owner and last-reviewed updated
Templates you can reuse
Dataset README skeleton
# Dataset: <name>
Owner: <team/contact>
Last reviewed: <YYYY-MM-DD>
Purpose: <1-2 sentences>
Schedule/SLA: <e.g., daily by 06:00 UTC>
Freshness expectation: <e.g., <24h>
Lineage: <upstream> -> <this> -> <downstream>
Schema:
| Column | Type | Nullable | Description |
|--------|------|----------|-------------|
Quality checks: <list with thresholds>
Known caveats: <edge cases>
Deprecations/changes: <summary or link to changelog section>
Runbook snippet
# Runbook: <pipeline>
Owner: <team/contact> | Escalation: <on-call>
Last reviewed: <YYYY-MM-DD>
Symptoms: <alerts/messages>
Quick checks: <commands/queries>
Common causes: <ordered list>
Fix steps: <numbered steps>
Rollback plan: <how>
Customer impact: <who/what>
Common mistakes and self-check
- Mistake: Updating docs quarterly. Fix: Update in the same PR as the change.
- Mistake: Docs without owner. Fix: Add Owner to every doc header.
- Mistake: No dates. Fix: Include Last reviewed and bump on each check.
- Mistake: Hidden changes. Fix: Keep a short, human-readable changelog.
- Mistake: Only success-path docs. Fix: Maintain runbooks for failure modes.
Self-check mini audit (5 minutes)
- Every dataset doc has Owner and Last reviewed
- Latest code change has a matching doc change
- SLAs and schedules match actual orchestration
- At least one runbook exists for critical pipelines
- Changelog entries exist for last two releases
Exercises
Do these to build the habit. The solutions are collapsible; try first, then peek.
Exercise 1: Turn a change into doc updates (mirrors ex1)
Scenario: A daily job for table user_sessions moved from 03:00 to 05:30 UTC; a new column device_type was added. Write the doc updates you would make.
Hints
- Think: README sections affected
- SLA, schema, changelog, runbook
Show solution
See the solution in the Exercises panel below (ex1).
Exercise 2: Create a PR checklist (mirrors ex2)
Draft a 6–8 line checklist that forces doc updates for any pipeline change.
Hints
- Cover schema, SLA, quality checks, runbooks
- Include owner/date fields
Show solution
See the solution in the Exercises panel below (ex2).
Practical projects
- Project 1: Add a Docs Impact section to your PR template and pilot it on one pipeline for two weeks
- Project 2: Migrate one dataset doc to the provided template, fill all fields, and backfill its last 5 changelog entries
- Project 3: Run a 30-minute docs audit on your top 3 pipelines; fix missing owner/date and mismatched SLAs
Learning path
- Start: Add Owner and Last reviewed to all critical docs
- Adopt: Add a Docs impact checklist to PRs
- Ritual: Weekly 15-minute doc health scan
- Improve: Keep per-dataset changelogs
- Automate: Add simple CI checks (e.g., require Owner field present) — optional but helpful
Next steps
Pick one pipeline or dataset and bring its docs to green today: owner set, last reviewed updated, SLA accurate, schema correct, and a fresh changelog entry.
Mini challenge
In under 20 minutes, update one runbook to include: symptoms, quick checks, and a one-step rollback. Mark the doc with today’s date.
Quick Test info
Take the quick test below to check your understanding. Anyone can take it; logged-in users will have their progress saved automatically.