Fix N+1 queries on admin workshop show - #2797
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The admin workshop show page issued ~6 scoped workshop_invitations queries per attending row (newbie?, flag_to_organisers?, recent_notes) because with_notes_and_their_authors preloads member_notes and attendance_warnings but not the member's other workshop invitations. For /admin/workshops/3824 this was 210 queries / 51s DB / 40s view / 221M allocations (~92s total). Collapse the three per-row lookups into a bounded query object (AdminWorkshopAttendeeFlags.for_members) computed once and memoised on the loaded member instances. 27 attendees now need 5 queries instead of ~159. Fixes #2796
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Closes #2796
Summary
The admin workshop show page issued ~6 scoped
workshop_invitationsqueries per attending row, becausewith_notes_and_their_authorspreloadsmember_notes/attendance_warningsbut not the member's other workshop invitations. For/admin/workshops/3824that was 210 queries / 51s DB / 40s view / 221M allocations (~92s total).This PR is scoped to the N+1 fix only. The RSVP dropdown itself is handled separately in #2798 (which replaces it with a dedicated RSVP page).
Fix
A new
AdminWorkshopAttendeeFlags.for_membersquery object collapses the three per-row lookups (newbie?,flag_to_organisers?,recent_notes) into a bounded set of aggregate queries, computed once and memoised on the loaded member instances. 27 attendees now need 5 queries instead of ~159.Verification
spec/queriers/admin_workshop_attendee_flags_spec.rb): semantics preserved, query count constant as member count grows.codebar_production_dump: flag computation 5 queries / 26ms for 27 attendees (old path ~159).Measured performance
/admin/workshops/3824(4,364 invitations, 27 attending) against the production dump, same session.End-to-end (browser dev-tools
DomContentLoaded): ~119 s on master vs ~118 s here.The N+1 fix removes ~6 queries per attendee row and ~90% of the query load, lowering DB/server pressure. It does not change perceived page load, because the remaining cost is the 4,337-option RSVP
<select>(a ~9 s server render plus a large HTML body the browser takes ~100 s to receive and parse). Removing that dropdown is #2798; the two PRs are complementary and the user-facing speedup comes from merging both.