## Problem Manual ordering (`relative_position`) of work items is scoped to the whole top-level group, but the position data is indexed leading with the leaf `namespace_id`. An ordered read therefore fans out across every namespace in the group instead of hitting one index range. On gitlab-org this measured ~15.7s for a board load and ~2.1s for the drag "next sibling" lookup (DB-Lab / production), blocking the UI mid-drag. ## Approach Add a `relative_positioning_namespace_id` column to `work_item_positions` holding each item's positioning root (top-level group, or the project namespace for personal projects), backed by a root-leading index `(relative_positioning_namespace_id, relative_position)`. Scope position reads by that root so they hit the index. On gitlab-org this brings board load to ~1.4ms and the drag neighbour lookup to ~5ms. Reads ship behind `read_relative_positions_from_work_item_positions` (default off). Builds on the `work_item_positions` table and bigint-range work from gitlab-org/gitlab#594236. ## Delivery Split into per-MR steps: add the root column + index, keep it fresh across group/project transfers, backfill existing rows, root-scope the reads behind the flag, then cut writes over to `work_item_positions`. GitLab.com rollout follows backfill finalization; self-managed follows the 19.5 required stop. A cleanup MR finalizes the backfill and drops the now-redundant leaf index. ## Progress Drag reordering on large groups (gitlab-org) is now under ~1.5s — on par with any other work item update (was ~7s / timeout). 🚀 - [x] Positioning-root column + root-leading index on `work_item_positions`; reads scoped behind `read_relative_positions_from_work_item_positions` (!248883) — enabled for gitlab-org; neighbour lookup ~7s/timeout → <100ms, board load ~15s → ms - [x] Backfill the new column — 100% on .com (!249251) - [x] Sibling-shift edge case (full positioning-root scan) now index-served — !251526, closed #621359 - [x] Board "move in progress" indicator delay 500ms → 1s so fast moves don't flash grey — !251812, closed #622470 - [ ] Roll the read flag out beyond gitlab-org — #607801 - [ ] Write cutover to `work_item_positions`, incl. widening to full bigint range + rebalance (fixes occasional slowdown in dense regions) — #612911 - [ ] Investigate remaining non-DB time on the reorder mutation — #619167 - [ ] Finalize backfill, drop the redundant leaf index