## Summary Roll out [the feature](https://gitlab.com/gitlab-org/gitlab/-/work_items/627208) currently behind the `mr_throughput_clickhouse_data_source` feature flag. - DRI: @ghosh-abhinaba - Team Slack channel: `#g_analytics_optimize` > [!note] > Process and guidance live in the docs — this issue is just the commands and a place to track the rollout. > "Rolling out" means incrementally enabling the flag on GitLab.com to validate stability — it is not the same as releasing the feature, which happens when the flag is removed. > [Feature flag controls](https://docs.gitlab.com/development/feature_flags/controls/) · [Feature flag lifecycle](https://handbook.gitlab.com/handbook/product-development/how-we-work/product-development-flow/feature-flag-lifecycle/#feature-flag-lifecycle) ## What could go wrong? Read-only change to one metric on one dashboard (MR throughput on the Duo & SDLC trends dashboard). No writes, no migration, no data loss risk. Blast radius is limited to groups with ClickHouse analytics enabled on GitLab.com — everyone else fails the gate and keeps the current Postgres path. The real risk is correctness, not availability: if Siphon replication lags or the ClickHouse `merge_requests` backfill is incomplete, throughput numbers will silently read low instead of erroring. Spot-check a few groups' ClickHouse throughput numbers against Postgres before going past 50%. If ClickHouse is unhealthy, the panel query fails and the dashboard shows a panel error — no worse than today's permanent loading state. Watch on https://dashboards.gitlab.net: ClickHouse service health and query latency, and Sidekiq/Siphon replication lag. ## Rollout Run all production `/chatops` in [`#production`](https://gitlab.slack.com/archives/C101F3796) and cross-post the results to `#g_analytics_optimize`. Background: [incremental rollout process](https://docs.gitlab.com/development/feature_flags/controls/#process), [feature actors](https://docs.gitlab.com/development/feature_flags/#feature-actors). **Non-production** The flag is inert on `--dev` (and anywhere Siphon/ClickHouse isn't available) because the `siphon_clickhouse_analytics` SaaS feature gate fails there — `--staging` is the only non-production target that actually exercises this path. ``` /chatops gitlab run feature set mr_throughput_clickhouse_data_source 50 --actors --dev --pre --staging --staging-ref /chatops gitlab run feature set mr_throughput_clickhouse_data_source true --dev --pre --staging --staging-ref ``` **Production** — percentage rollout (wait >= 15 min between steps, watch dashboards): ``` /chatops gitlab run feature set mr_throughput_clickhouse_data_source <percentage> --actors ``` Or target specific actors instead. The actor is the root ancestor namespace (a group), so only `--group=` is valid here — `--project=` and `--user=` don't match the gate and won't do anything: ``` /chatops gitlab run feature set --group=gitlab-org,gitlab-com mr_throughput_clickhouse_data_source true ``` ## Before global rollout Confirm the relevant gotchas before going to 100% — see [enabling a feature for GitLab.com](https://docs.gitlab.com/development/feature_flags/controls/#enabling-a-feature-for-gitlabcom): - [Docs + version history](https://docs.gitlab.com/development/documentation/feature_flags/) updated - [Breaking changes](https://docs.gitlab.com/development/documentation/release_notes/#deprecations-removals-and-breaking-changes) announced, if any - [Change management issue](https://handbook.gitlab.com/handbook/engineering/infrastructure-platforms/change-management/#feature-flags-and-the-change-management-process) opened, if required - [External API consumers](https://docs.gitlab.com/development/feature_flags/#do-not-use-feature-flags-in-external-api-consumers) handled with a fail-open mechanism, if applicable ## Cleanup Remove the flag once [deemed stable](https://handbook.gitlab.com/handbook/product-development/how-we-work/product-development-flow/feature-flag-lifecycle/#feature-flag-lifecycle) — see [cleaning up](https://docs.gitlab.com/development/feature_flags/controls/#cleaning-up). Track it here, or open a follow-up [Feature Flag Cleanup issue](https://gitlab.com/gitlab-org/gitlab/-/work_items/new?description_template=Feature%20Flag%20Cleanup). Remove the flag and its YAML definition from the codebase, then: ``` /chatops gitlab run release check https://gitlab.com/gitlab-org/gitlab/-/merge_requests/253107 19.3 /chatops gitlab run feature delete mr_throughput_clickhouse_data_source --dev --pre --staging --staging-ref --production ``` ## Rollback ``` /chatops gitlab run feature set mr_throughput_clickhouse_data_source false # production /chatops gitlab run feature set mr_throughput_clickhouse_data_source false --dev --pre --staging --staging-ref # non-production /chatops gitlab run feature delete mr_throughput_clickhouse_data_source --dev --pre --staging --staging-ref --production # remove entirely ```