Eliminate N+1 queries in /api/groups/:id
In https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/15475/diffs, a
significant amount of work went into eliminating N+1 queries in the
/api/groups/:id/projects endpoint. We can reuse the
Entities::Project.prepare_relation call on the projects.
In a group with 2,573 projects on GitLab.com, this change significantly improves performance:
- 18019 SQL queries down to 21
- Time spent in DB: 70 s down to 384 ms
This endpoint is by far the worst we have of all our API endpoints:
Edited by Stan Hu