<!-- Title suggestion: [FF] `export_uploads_via_project_uploads_index` -- <short description> --> ## Summary This issue is to roll out [the feature](https://gitlab.com/gitlab-org/gitlab/-/work_items/554957) on production, that is currently behind the `export_uploads_via_project_uploads_index` feature flag. ## Owners - Most appropriate Slack channel to reach out to: `g_import` - Best individual to reach out to: @rodrigo.tomonari ## Expectations ### What are we expecting to happen? The flag switches the upload query used by project export (`Gitlab::ImportExport::UploadsManager#each_uploader`) from the `@project.uploads` association (which filters by `model_id`) to the new `Upload.for_project` scope (which filters by the `project_id` sharding key plus `model_type = 'Project'`). The `project_id` predicate lets Postgres prune to the `project_uploads` partition and serve the `ORDER BY id LIMIT 100` batches used by `find_each` directly from the `index_project_uploads_on_project_id_and_id` index. Expected outcome: - **No user-visible behavior change.** Exports copy the same set of upload files, and the project avatar is still excluded (the exclusion moved from SQL to Ruby). `model_id` and `project_id` hold the same value for `Project` uploads, so the result set is identical. - **Faster, lighter upload queries during export**, especially for projects with many uploads. Example query plans for `gitlab-org/gitlab` (~491k `Project` uploads): - Today (and the flag-disabled path): `Index Scan` on `project_uploads_pkey` walking `id` order and filtering — ~52,266 buffers (~20 ms warm, ~1.4 s cold). - Flag-enabled with the index present: `Index Scan` on `index_project_uploads_on_project_id_and_id` — ~96 buffers, sub-millisecond. - Reduced buffer/IO load on the primary from export upload scans, and lower `ProjectExportWorker` time spent in this query. Actor: **project** (`Feature.enabled?(:export_uploads_via_project_uploads_index, project)`), so rollout is per-project. ### What can go wrong and how would we detect it? - **The `index_project_uploads_on_project_id_and_id` index isn't present yet.** It was added by a post-deployment migration (`20260519162209`, milestone 19.1), which on GitLab.com runs after code deploy and can be delayed. If the flag is enabled before the index exists, the planner falls back to the same `project_uploads_pkey` scan used today — i.e. **no regression vs. current behavior**, just no speed-up. Detection: confirm the index with `\d index_project_uploads_on_project_id_and_id` on a replica before enabling; watch export query duration not improving. - **Incomplete or mismatched `project_id` sharding key → exported upload set differs (data-completeness bug).** This is the only correctness risk, and it is mitigated: `project_id` has a validated `NOT NULL` constraint (milestone 18.7), the partitioned-uploads backfill is finalized, and a trigger keeps `project_id` in sync with `model_id` on write. Detection: a drop in exported upload counts or customer reports of missing files in exported archives; export job error rate. - **Unexpectedly slow plan for an atypical project** (e.g. uploads sitting very late in `id` order). Because the flag-disabled path runs the equivalent `model_id`-filtered scan, any such case already exists in production unchanged. Detection: Postgres slow-query logs / `marginalia` comments scoped to `UploadsManager`, and `ProjectExportWorker` duration. How we detect and where to look: - **Sidekiq / export workers:** [Sidekiq dashboards](https://log.gprd.gitlab.net/app/r/s/YBgRF) for `ProjectExportWorker` — job duration, failure rate, queue latency. - **Database:** [PostgreSQL primary dashboards](https://dashboards.gitlab.net) for buffer/IO and slow queries on `project_uploads`. - **Logs:** Kibana — Sidekiq logs in `pubsub-sidekiq-inf-gprd*` (export worker errors/duration) and Rails logs in `pubsub-rails-inf-gprd-*`. - **Errors:** Sentry for exceptions raised from `Gitlab::ImportExport::UploadsManager`. Rollback: disable the flag (`/chatops gitlab run feature set export_uploads_via_project_uploads_index false`) to instantly revert to the `@project.uploads` path. No data migration is involved, so rollback is safe at any point. ## Rollout Steps Note: Please make sure to run the chatops commands in the Slack channel that gets impacted by the command. ### Rollout on non-production environments - Verify the MR with the feature flag is merged to `master` and has been deployed to non-production environments with `/chatops gitlab run auto_deploy status <merge-commit-of-your-feature>` <!-- Delete Incremental roll out if it is not relevant to this deploy --> - [x] Deploy the feature flag at a percentage (recommended percentage: 50%) with `/chatops gitlab run feature set export_uploads_via_project_uploads_index <rollout-percentage> --actors --dev --pre --staging --staging-ref` - [x] Monitor that the error rates did not increase (repeat with a different percentage as necessary). <!-- End of block for deletes --> - [x] Enable the feature globally on non-production environments with `/chatops gitlab run feature set export_uploads_via_project_uploads_index true --dev --pre --staging --staging-ref` - [x] Verify that the feature works as expected. The best environment to validate the feature in is [`staging-canary`](https://about.gitlab.com/handbook/engineering/infrastructure/environments/#staging-canary) as this is the first environment deployed to. Make sure you are [configured to use canary](https://next.gitlab.com/). - [x] If the feature flag causes end-to-end tests to fail, disable the feature flag on staging to avoid blocking [deployments](https://about.gitlab.com/handbook/engineering/deployments-and-releases/deployments/). - See [`#e2e-run-staging` Slack channel](https://gitlab.enterprise.slack.com/archives/CBS3YKMGD) and look for the following messages: - test kicked off: `Feature flag export_uploads_via_project_uploads_index has been set to true on **gstg**` - test result: `This pipeline was triggered due to toggling of export_uploads_via_project_uploads_index feature flag` If you encounter end-to-end test failures and are unable to diagnose them, you may reach out to the [`#s_developer_experience` Slack channel](https://gitlab.enterprise.slack.com/archives/C07TWBRER7H) for assistance. Note that end-to-end test failures on `staging-ref` [don't block deployments](https://about.gitlab.com/handbook/engineering/infrastructure/environments/staging-ref/#how-to-use-staging-ref). ### Before production rollout - [ ] If the change is significant and you wanted to announce in [#whats-happening-at-gitlab](https://gitlab.enterprise.slack.com/archives/C0259241C), it best to do it before rollout to `gitlab-org/gitlab-com`. ### Specific rollout on production For visibility, all `/chatops` commands that target production must be executed in the [`#production` Slack channel](https://gitlab.slack.com/archives/C101F3796) and cross-posted (with the command results) to the responsible team's Slack channel. - Ensure that the feature MRs have been deployed to both production and canary with `/chatops gitlab run auto_deploy status <merge-commit-of-your-feature>` - [x] Depending on the [type of actor](https://docs.gitlab.com/development/feature_flags/#feature-actors) you are using, pick one of these options: - For **project-actor**: `/chatops gitlab run feature set --project=gitlab-org/gitlab,gitlab-org/gitlab-foss,gitlab-com/www-gitlab-com export_uploads_via_project_uploads_index true` - For **group-actor**: `/chatops gitlab run feature set --group=gitlab-org,gitlab-com export_uploads_via_project_uploads_index true` - For **user-actor**: `/chatops gitlab run feature set --user=<gitlab-username-of-dri> export_uploads_via_project_uploads_index true` - For **all internal users**: `/chatops gitlab run feature set --feature-group=gitlab_team_members export_uploads_via_project_uploads_index true` - [x] Verify that the feature works for the specific actors. ### Preparation before global rollout - [ ] Set a milestone to this rollout issue to signal for enabling and removing the feature flag when it is stable. - [ ] Check if the feature flag change needs to be accompanied with a [change management issue](https://about.gitlab.com/handbook/engineering/infrastructure-platforms/change-management/#feature-flags-and-the-change-management-process). Cross link the issue here if it does. - [ ] Ensure that you or a representative in development can be available for at least 2 hours after feature flag updates in production. If a different developer will be covering, or an exception is needed, please inform the oncall SRE by using the `@sre-oncall` Slack alias. - [ ] Ensure that documentation exists for the feature, and the [version history text](https://docs.gitlab.com/development/documentation/feature_flags/#add-history-text) has been updated. - [ ] Ensure that any breaking changes have been announced following the [release post process](https://about.gitlab.com/handbook/marketing/blog/release-posts/#deprecations-removals-and-breaking-changes) to ensure GitLab customers are aware. - [ ] Notify the [`#support_gitlab-com` Slack channel](https://gitlab.slack.com/archives/C4XFU81LG) and your team channel ([more guidance when this is necessary in the dev docs](https://docs.gitlab.com/development/feature_flags/controls/#communicate-the-change)). - [ ] If this flag is or may be queried by external API consumers (for example, IDE extensions, Duo CLI, or CI integrations), follow the [external API consumer guidance](https://docs.gitlab.com/development/feature_flags/#do-not-use-feature-flags-in-external-api-consumers) and ensure a fail-open mechanism is in place before the rollout milestone is finalised. ### Global rollout on production For visibility, all `/chatops` commands that target production must be executed in the [`#production` Slack channel](https://gitlab.slack.com/archives/C101F3796) and cross-posted (with the command results) to the responsible team's Slack channel. - [x] [Incrementally roll out](https://docs.gitlab.com/development/feature_flags/controls/#process) the feature on production. - Example: `/chatops gitlab run feature set export_uploads_via_project_uploads_index <rollout-percentage> --actors`. - Between every step wait for at least 15 minutes and monitor the appropriate graphs on https://dashboards.gitlab.net. - [x] After the feature has been 100% enabled, wait for [at least one day before releasing the feature](#release-the-feature). ### (Optional) Release the feature with the feature flag **WARNING:** This approach has the downside that it makes it difficult for us to [clean up](https://docs.gitlab.com/development/feature_flags/controls/#cleaning-up) the flag. For example, on-premise users could disable the feature on their GitLab instance. But when you remove the flag at some point, they suddenly see the feature as enabled and they can't roll it back to the previous behavior. To avoid this potential breaking change, use this approach only for urgent matters. <details><summary>See instructions if you're sure about enabling the feature globally through the feature flag definition</summary> If you're still unsure whether the feature is [deemed stable](https://about.gitlab.com/handbook/product-development-flow/feature-flag-lifecycle/#including-a-feature-behind-feature-flag-in-the-final-release) but want to release it in the current milestone, you can change the default state of the feature flag to be enabled. To do so, follow these steps: - [ ] Create a merge request with the following changes. - [ ] If feature was enabled for various actors, ensure the feature has been enabled globally on production `/chatops gitlab run feature get export_uploads_via_project_uploads_index`. If the feature has not been globally enabled then enable the feature globally using: `/chatops gitlab run feature set export_uploads_via_project_uploads_index true` - [ ] Set the `default_enabled` attribute in [the feature flag definition](https://docs.gitlab.com/development/feature_flags/#feature-flag-definition-and-validation) to `true`. - [ ] Decide [which changelog entry](https://docs.gitlab.com/development/feature_flags/#changelog) is needed. - [ ] Ensure that the default-enabling MR has been included in the release package. If the merge request was deployed before [the monthly release was tagged](https://about.gitlab.com/handbook/engineering/releases/#self-managed-releases-1), the feature can be officially announced in a release blog post: `/chatops gitlab run release check <merge-request-url> <milestone>` - [ ] After the default-enabling MR has been deployed, clean up the feature flag from all environments by running these chatops command in the `#production` channel: `/chatops gitlab run feature delete export_uploads_via_project_uploads_index --dev --pre --staging --staging-ref --production` - [ ] Close [the feature issue](<feature-issue-link>) to indicate the feature will be released in the current milestone. - [ ] Set the next milestone to this rollout issue for scheduling [the flag removal](#release-the-feature). - [ ] (Optional) You can [create a separate issue](https://gitlab.com/gitlab-org/gitlab/-/issues/new?description_template=Feature%20Flag%20Cleanup) for scheduling the steps below to [Release the feature](#release-the-feature). - [ ] Set the title to "[FF] `export_uploads_via_project_uploads_index` - Cleanup". - [ ] Execute the `/copy_metadata <this-rollout-issue-link>` quick action to copy the labels from this rollout issue. - [ ] Link this rollout issue as a related issue. - [ ] Close this rollout issue. </details> ### Release the feature After the feature has been [deemed stable](https://about.gitlab.com/handbook/product-development-flow/feature-flag-lifecycle/#including-a-feature-behind-feature-flag-in-the-final-release), the [clean up](https://docs.gitlab.com/development/feature_flags/controls/#cleaning-up) should be done as soon as possible to permanently enable the feature and reduce complexity in the codebase. You can either [create a follow-up issue for Feature Flag Cleanup](https://gitlab.com/gitlab-org/gitlab/-/issues/new?description_template=Feature%20Flag%20Cleanup) or use the checklist below in this same issue. <!-- The checklist here is to help stakeholders keep track of the feature flag status --> - [ ] Create a merge request to remove the `export_uploads_via_project_uploads_index` feature flag. Ask for review/approval/merge as usual. The MR should include the following changes: - Remove all references to the feature flag from the codebase. - Remove the YAML definitions for the feature from the repository. - [ ] Ensure that the cleanup MR has been included in the release package. If the merge request was deployed before [the monthly release was tagged](https://about.gitlab.com/handbook/engineering/releases/#self-managed-releases-1), the feature can be officially announced in a release blog post: `/chatops gitlab run release check <merge-request-url> <milestone>` - [ ] Close [the feature issue](<feature-issue-link>) to indicate the feature will be released in the current milestone. - [ ] Once the cleanup MR has been deployed to production, clean up the feature flag from all environments by running these chatops command in `#production` channel: `/chatops gitlab run feature delete export_uploads_via_project_uploads_index --dev --pre --staging --staging-ref --production` - [ ] Close this rollout issue. ## Rollback Steps - [ ] This feature can be disabled on production by running the following Chatops command: ``` /chatops gitlab run feature set export_uploads_via_project_uploads_index false ``` - [ ] Disable the feature flag on non-production environments: ``` /chatops gitlab run feature set export_uploads_via_project_uploads_index false --dev --pre --staging --staging-ref ``` - [ ] Delete feature flag from all environments: ``` /chatops gitlab run feature delete export_uploads_via_project_uploads_index --dev --pre --staging --staging-ref --production ```