Code Review Process ER Diagram Template

An ER diagram for the code review process captures every entity involved in taking a pull request from creation to merge—developers, reviewers, pull requests, comments, approvals, and repositories—along with the relationships that connect them. Each entity holds its own attributes: a pull request tracks its status, branch name, and timestamps; a review comment stores its body, line reference, and resolution state; an approval records who signed off and when. By modeling these relationships explicitly, teams gain a shared, unambiguous reference for how their review workflow is structured in the underlying data, whether that data lives in GitHub, GitLab, Jira, or a custom internal tool.

## When to Use This Template

Reach for this ER diagram template when you are designing or auditing the database schema that powers a code review tool, onboarding engineers to an existing review system, or documenting compliance requirements around who approved what and when. It is equally useful when integrating a third-party review platform with internal systems—having a clear entity map prevents mismatched field assumptions that cause bugs at the integration layer. Product managers and engineering leads also use it during sprint planning to align on what data needs to be captured before building new review-related features such as automated checks, SLA tracking, or reviewer assignment rules.

## Common Mistakes to Avoid

One frequent error is collapsing the PR and the code diff into a single entity. A pull request is a workflow object with status and participants, while a diff or file change is a content object with its own lifecycle; keeping them separate prevents schema bloat and query confusion. Another mistake is omitting the review round or iteration entity. Code review rarely ends after one pass, and without modeling review rounds you lose the ability to track how many cycles a PR went through before merge—a key metric for process improvement. Finally, avoid treating approval as a simple boolean on the PR entity. Approval belongs as its own entity linked to both a reviewer and a PR, so you can support multiple required approvers, capture timestamps, and handle approval revocations cleanly. Taking the time to normalize these relationships in your ER diagram before writing a single line of schema SQL will save significant refactoring effort later.