docs/developer_portal/contributing/code-review.md

---
title: Code Review Process
sidebar_position: 4
---

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# Code Review Process

Understand how code reviews work in Apache Superset and how to participate effectively.

## Overview

Code review is a critical part of maintaining code quality and sharing knowledge across the team. Every change to Superset goes through peer review before merging.

## For Authors

### Preparing for Review

#### Before Requesting Review
- [ ] Self-review your changes
- [ ] Ensure CI checks pass
- [ ] Add comprehensive tests
- [ ] Update documentation
- [ ] Fill out PR template completely
- [ ] Add screenshots for UI changes

#### Self-Review Checklist
```bash
# View your changes
git diff upstream/master

# Check for common issues:
# - Commented out code
# - Debug statements (console.log, print)
# - TODO comments that should be addressed
# - Hardcoded values that should be configurable
# - Missing error handling
# - Performance implications
```

### Requesting Review

#### Auto-Assignment
GitHub will automatically request reviews based on CODEOWNERS file.

#### Manual Assignment
For specific expertise, request additional reviewers:
- Frontend changes: Tag frontend experts
- Backend changes: Tag backend experts
- Security changes: Tag security team
- Database changes: Tag database experts

#### Review Request Message
```markdown
@reviewer This PR implements [feature]. Could you please review:
1. The approach taken in [file]
2. Performance implications of [change]
3. Security considerations for [feature]

Thanks!
```

### Responding to Feedback

#### Best Practices
- **Be receptive**: Reviews improve code quality
- **Ask questions**: Clarify if feedback is unclear
- **Explain decisions**: Share context for your choices
- **Update promptly**: Address feedback in timely manner

#### Comment Responses
```markdown
# Acknowledging
"Good catch! Fixed in [commit hash]"

# Explaining
"I chose this approach because [reason]. Would you prefer [alternative]?"

# Questioning
"Could you elaborate on [concern]? I'm not sure I understand the issue."

# Disagreeing respectfully
"I see your point, but I think [current approach] because [reason]. What do you think?"
```

## For Reviewers

### Review Responsibilities

#### What to Review
1. **Correctness**: Does the code do what it claims?
2. **Design**: Is the approach appropriate?
3. **Clarity**: Is the code readable and maintainable?
4. **Testing**: Are tests comprehensive?
5. **Performance**: Any performance concerns?
6. **Security**: Any security issues?
7. **Documentation**: Is it well documented?

### Review Checklist

#### Functionality
- [ ] Feature works as described
- [ ] Edge cases are handled
- [ ] Error handling is appropriate
- [ ] Backwards compatibility maintained

#### Code Quality
- [ ] Follows project conventions
- [ ] No code duplication
- [ ] Clear variable/function names
- [ ] Appropriate abstraction levels
- [ ] SOLID principles followed

#### Testing
- [ ] Unit tests for business logic
- [ ] Integration tests for APIs
- [ ] E2E tests for critical paths
- [ ] Tests are maintainable
- [ ] Good test coverage

#### Security
- [ ] Input validation
- [ ] SQL injection prevention
- [ ] XSS prevention
- [ ] CSRF protection
- [ ] Authentication/authorization checks
- [ ] No sensitive data in logs

#### Performance
- [ ] Database queries optimized
- [ ] No N+1 queries
- [ ] Appropriate caching
- [ ] Frontend bundle size impact
- [ ] Memory usage considerations

### Providing Feedback

#### Effective Comments

```python
# ✅ Good: Specific and actionable
"This query could cause N+1 problems. Consider using
`select_related('user')` to fetch users in a single query."

# ❌ Bad: Vague
"This doesn't look right."
```

```typescript
// ✅ Good: Suggests improvement
"Consider using useMemo here to prevent unnecessary
re-renders when dependencies haven't changed."

// ❌ Bad: Just criticism
"This is inefficient."
```

#### Comment Types

**Use GitHub's comment types:**
- **Comment**: General feedback or questions
- **Approve**: Changes look good
- **Request Changes**: Must be addressed before merge

**Prefix conventions:**
- `nit:` Minor issue (non-blocking)
- `suggestion:` Recommended improvement
- `question:` Seeking clarification
- `blocker:` Must be fixed
- `praise:` Highlighting good work

#### Examples

```markdown
nit: Consider renaming `getData` to `fetchUserData` for clarity

suggestion: This could be simplified using Array.reduce()

question: Is this intentionally not handling the error case?

blocker: This SQL is vulnerable to injection. Please use parameterized queries.

praise: Excellent test coverage! 👍
```

## Review Process

### Timeline

#### Expected Response Times
- **Initial review**: Within 2-3 business days
- **Follow-up review**: Within 1-2 business days
- **Critical fixes**: ASAP (tag in Slack)

#### Escalation
If no response after 3 days:
1. Ping reviewer in PR comments
2. Ask in #development Slack channel
3. Tag @apache/superset-committers

### Approval Requirements

#### Minimum Requirements
- **1 approval** from a committer for minor changes
- **2 approvals** for significant features
- **3 approvals** for breaking changes

#### Special Cases
- **Security changes**: Require security team review
- **API changes**: Require API team review
- **Database migrations**: Require database expert review
- **UI/UX changes**: Require design review

### Merge Process

#### Who Can Merge
- Committers with write access
- After all requirements met
- CI checks must pass

#### Merge Methods
- **Squash and merge**: Default for feature PRs
- **Rebase and merge**: For clean history
- **Create merge commit**: Rarely used

#### Merge Checklist
- [ ] All CI checks green
- [ ] Required approvals obtained
- [ ] No unresolved conversations
- [ ] PR title follows conventions
- [ ] Milestone set (if applicable)

## Review Etiquette

### Do's
- ✅ Be kind and constructive
- ✅ Acknowledge time and effort
- ✅ Provide specific examples
- ✅ Suggest solutions
- ✅ Praise good work
- ✅ Consider cultural differences
- ✅ Focus on the code, not the person

### Don'ts
- ❌ Use harsh or dismissive language
- ❌ Bikeshed on minor preferences
- ❌ Review when tired or frustrated
- ❌ Make personal attacks
- ❌ Ignore the PR description
- ❌ Demand perfection

## Becoming a Reviewer

### Path to Reviewer
1. **Contribute regularly**: Submit quality PRs
2. **Participate in discussions**: Share knowledge
3. **Review others' code**: Start with comments
4. **Build expertise**: Focus on specific areas
5. **Get nominated**: By existing committers

### Reviewer Expectations
- Review PRs in your area of expertise
- Respond within reasonable time
- Mentor new contributors
- Maintain high standards
- Stay current with best practices

## Advanced Topics

### Reviewing Large PRs

#### Strategy
1. **Request splitting**: Ask to break into smaller PRs
2. **Review in phases**:
   - Architecture/approach first
   - Implementation details second
   - Tests and docs last
3. **Use draft reviews**: Save comments and submit together

### Cross-Team Reviews

#### When Needed
- Changes affecting multiple teams
- Shared components/libraries
- API contract changes
- Database schema changes

### Performance Reviews

#### Tools
```python
# Backend performance
import cProfile
import pstats

# Profile the code
cProfile.run('function_to_profile()', 'stats.prof')
stats = pstats.Stats('stats.prof')
stats.sort_stats('cumulative').print_stats(10)
```

```typescript
// Frontend performance
// Use React DevTools Profiler
// Chrome DevTools Performance tab
// Lighthouse audits
```

## Resources

### Internal
- [Coding Guidelines](../guidelines/design-guidelines)
- [Testing Guide](../testing/overview)
- [Extension Architecture](../extensions/architecture)

### External
- [Google's Code Review Guide](https://google.github.io/eng-practices/review/)
- [Best Practices for Code Review](https://smartbear.com/learn/code-review/best-practices-for-peer-code-review/)
- [The Art of Readable Code](https://www.oreilly.com/library/view/the-art-of/9781449318482/)

Next: [Reporting issues effectively](./issue-reporting)