This patch makes sure GitLab does not save the refs to the filesystem
each time the deployment is updated. This will save some IO although I
expect the impact to be minimal.
Keep-around refs for deployments were only introduced in 8.10, so any
deployment created in 8.9 could have a SHA pointing to a commit that no
longer exists in the repository. We can't do anything useful with those
deployments, so make `#includes_commit?` always return false for those.
- Don't use `TableReferences` - using `.arel_table` is shorter!
- Move some database-related code to `Gitlab::Database`
- Remove the `MergeRequest#issues_closed` and
`Issue#closed_by_merge_requests` associations. They were either
shadowing or were too similar to existing methods. They are not being
used anywhere, so it's better to remove them to reduce confusion.
- Use Rails 3-style validations
- Index for `MergeRequest::Metrics#first_deployed_to_production_at`
- Only include `CycleAnalyticsHelpers::TestGeneration` for specs that
need it.
- Other minor refactorings.
- Move things common to `Issue` and `MergeRequest` into `Issuable`
- Move more database-specific functions into `Gitlab::Database`
- Indentation changes and other minor refactorings.
1. Change multiple updates to a single `update_all`
2. Use cascading deletes
3. Extract an average function for the database median.
4. Move database median to `lib/gitlab/database`
5. Use `delete_all` instead of `destroy_all`
6. Minor refactoring
