perf: preload organiser roles to eliminate N+1 queries in event_organiser?#2692
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…iser? Replaces per-event has_role?(:organiser) calls with a single query that loads all organiser roles upfront, then does in-memory hash lookups. Reduces permission queries for a page with 30 events from ~88 to ~2 (98% reduction). Measured against dev data with an organiser user. - Adds private organising_events method (cached) that plucks all organiser role (resource_type, resource_id) pairs - Adds private admin? method (cached) for the admin fallback check - Handles nil chapter for events/meetings that use HABTM chapters
jonodrew
approved these changes
Jul 7, 2026
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This optimisation originally came from @jonodrew's work in #2305. That PR had deeper merge conflicts with a rewritten EventsController, but the hash-lookup approach for
event_organiser?was independently useful and is extracted here.What changed
event_organiser?inMemberPresenterwas callinghas_role?(:organiser, event)per event — one permission query (plus join) for each event on the page. For an organiser, this fires for every event/meeting rendered in the listing.The replacement preloads all organiser roles into a
{ resource_type => [resource_id] }hash with a single query, then does in-memory lookups.When this applies
Only for organiser users viewing event listing pages. The call site in
_event.html.hamlis guarded by@user.organiser?, so non-organisers never hit this path. The pages that benefit:/,/dashboard) — rendering upcoming workshops/:slug) — upcoming and past workshops/events/upcoming,/events/past) — paginated event listsBenchmarks
Against production data (29k members, 2.5k workshops, user with 258 organiser roles, 50 workshops):
The 2 remaining queries are: one
SELECTto bulk-load all organiser role rows, and oneSELECTfor the memoised admin check.