perf: eliminate N+1 queries across list views and add covering indexes

CHANGELOG.md

@@ -7,8 +7,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- Eliminate N+1 queries on the queues index — replaced per-queue `COUNT` loop with a single `GROUP BY queue_name` aggregation
+- `CacheSizeStats#buckets` now runs a single `SUM(CASE WHEN ...)` aggregation instead of one `COUNT` query per size bucket; `#total` is derived from the already-computed bucket counts (no extra query)
+- `JobsController` filter options (queue and priority dropdowns) now resolved with one `pluck` call instead of two separate queries
+
 ### Added
 
+- Covering indexes added to dummy app schema — `solid_queue_jobs (finished_at, created_at)` for the slow-job scan; `(queue_name, created_at)` on `solid_queue_scheduled_executions` and `solid_queue_blocked_executions` (both previously lacked a queue-name index)
 - Install generator — `rails generate solid_stack_web:install` creates `config/initializers/solid_stack_web.rb` with every config option documented inline and injects the mount line into `config/routes.rb`
 - `SolidStackWeb.mount_path` — returns the path at which the engine is mounted in the host app, derived automatically from routes; use `link_to "Dashboard", SolidStackWeb.mount_path` to link to the dashboard without hardcoding the path
 - Accessibility pass — skip-to-content link; ARIA labels on all navigation elements; `scope="col"` on every table header; visually-hidden "Actions" label on empty action-column headers; `aria-sort` on active sort columns in stats and cache entries; `aria_label: "Pagination"` on all pagination navs; `.sqw-sr-only` and `.sqw-skip-link` CSS utilities added to base stylesheet

README.md

@@ -29,6 +29,16 @@ mount SolidStackWeb::Engine, at: "/solid_stack"
 
 The dashboard will be available at `/solid_stack` (or whatever path you choose).
 
+### Install generator
+
+Run the install generator to create a documented initializer and wire up the mount point in one step:
+
+```bash
+rails generate solid_stack_web:install
+```
+
+This creates `config/initializers/solid_stack_web.rb` with every configuration option commented inline, and injects `mount SolidStackWeb::Engine, at: "/solid_stack"` into `config/routes.rb`.
+
 ---
 
 ## Metrics endpoint
@@ -88,16 +98,6 @@ The `authenticate` block is evaluated in the context of each request's controlle
 link_to "Queue Dashboard", SolidStackWeb.mount_path
 ```
 
-### Install generator
-
-Run the install generator to create a documented initializer and wire up the mount point in one step:
-
-```bash
-rails generate solid_stack_web:install
-```
-
-This creates `config/initializers/solid_stack_web.rb` with every configuration option commented inline, and injects `mount SolidStackWeb::Engine, at: "/solid_stack"` into `config/routes.rb`.
-
 ---
 
 ## Solid Queue

ROADMAP.md

@@ -11,7 +11,6 @@ The path to v1.0.0 is staged: first achieve feature parity with `solid_queue_das
 > _Make it easy to adopt and easy to contribute to._
 
 ### Remaining
-- **Query optimisation** — eliminate N+1 queries across all list views; add covering indexes to the dummy app schema
 - **Error pages** — engine-scoped 404/500 views so errors stay within the dashboard chrome
 - **Changelog-driven upgrade notes** — `UPGRADING.md` for any breaking configuration changes
 

app/controllers/solid_stack_web/jobs_controller.rb

@@ -5,8 +5,11 @@ class JobsController < ApplicationController
     before_action :require_discardable, only: [:destroy]
 
     def index
-      @queue_options    = Job::EXECUTION_MODELS[@status].joins(:job).distinct.pluck("solid_queue_jobs.queue_name").sort
-      @priority_options = Job::EXECUTION_MODELS[@status].joins(:job).distinct.pluck("solid_queue_jobs.priority").sort
+      pairs = Job::EXECUTION_MODELS[@status].joins(:job)
+                .distinct
+                .pluck("solid_queue_jobs.queue_name", "solid_queue_jobs.priority")
+      @queue_options    = pairs.map(&:first).uniq.sort
+      @priority_options = pairs.map(&:last).uniq.sort
 
       respond_to do |format|
         format.html { @pagy, @executions = pagy(filtered_scope) }

app/controllers/solid_stack_web/queues_controller.rb

@@ -1,16 +1,11 @@
 module SolidStackWeb
   class QueuesController < ApplicationController
     def index
-      queue_names = ::SolidQueue::ReadyExecution.distinct.pluck(:queue_name)
-      paused      = ::SolidQueue::Pause.pluck(:queue_name).to_set
+      counts = ::SolidQueue::ReadyExecution.group(:queue_name).count
+      paused = ::SolidQueue::Pause.pluck(:queue_name).to_set
 
-      @queues = queue_names.sort.map do |name|
-        {
-          name:   name,
-          size:   ::SolidQueue::ReadyExecution.where(queue_name: name).count,
-          paused: paused.include?(name)
-        }
-      end
+      @queues = counts.map { |name, size| { name:, size:, paused: paused.include?(name) } }
+                      .sort_by { |q| q[:name] }
 
       @sparklines = @queues.each_with_object({}) do |queue, h|
         h[queue[:name]] = QueueDepthSparkline.new(queue[:name])

app/models/solid_stack_web/cache_size_stats.rb

@@ -18,16 +18,20 @@ def top_entries
     end
 
     def buckets
-      @buckets ||= BUCKETS.map do |b|
-        scope = ::SolidCache::Entry.all
-        scope = scope.where("byte_size >= ?", b[:min]) if b[:min] > 0
-        scope = scope.where("byte_size < ?",  b[:max]) if b[:max]
-        { label: b[:label], count: scope.count }
+      @buckets ||= begin
+        row = ::SolidCache::Entry.pluck(
+          Arel.sql("COALESCE(SUM(CASE WHEN byte_size < 1024 THEN 1 ELSE 0 END), 0)"),
+          Arel.sql("COALESCE(SUM(CASE WHEN byte_size >= 1024 AND byte_size < 10240 THEN 1 ELSE 0 END), 0)"),
+          Arel.sql("COALESCE(SUM(CASE WHEN byte_size >= 10240 AND byte_size < 102400 THEN 1 ELSE 0 END), 0)"),
+          Arel.sql("COALESCE(SUM(CASE WHEN byte_size >= 102400 AND byte_size < 1048576 THEN 1 ELSE 0 END), 0)"),
+          Arel.sql("COALESCE(SUM(CASE WHEN byte_size >= 1048576 THEN 1 ELSE 0 END), 0)")
+        ).first || Array.new(5, 0)
+        BUCKETS.zip(row).map { |b, count| { label: b[:label], count: count.to_i } }
       end
     end
 
     def total
-      @total ||= ::SolidCache::Entry.count
+      @total ||= buckets.sum { |b| b[:count] }
     end
   end
 end

spec/dummy/db/schema.rb

@@ -10,6 +10,7 @@
     t.index ["concurrency_key", "priority", "job_id"], name: "index_solid_queue_blocked_executions_for_release"
     t.index ["expires_at", "concurrency_key"], name: "index_solid_queue_blocked_executions_for_maintenance"
     t.index ["job_id"], name: "index_solid_queue_blocked_executions_on_job_id", unique: true
+    t.index ["queue_name", "created_at"], name: "index_solid_queue_blocked_executions_on_queue_name"
   end
 
   create_table "solid_queue_claimed_executions", force: :cascade do |t|
@@ -41,6 +42,7 @@
     t.index ["active_job_id"], name: "index_solid_queue_jobs_on_active_job_id"
     t.index ["class_name"], name: "index_solid_queue_jobs_on_class_name"
     t.index ["finished_at"], name: "index_solid_queue_jobs_on_finished_at"
+    t.index ["finished_at", "created_at"], name: "index_solid_queue_jobs_on_finished_at_and_created_at"
     t.index ["queue_name", "finished_at"], name: "index_solid_queue_jobs_for_filtering"
     t.index ["scheduled_at", "finished_at"], name: "index_solid_queue_jobs_for_alerting"
   end
@@ -107,6 +109,7 @@
     t.datetime "scheduled_at", null: false
     t.datetime "created_at", null: false
     t.index ["job_id"], name: "index_solid_queue_scheduled_executions_on_job_id", unique: true
+    t.index ["queue_name", "created_at"], name: "index_solid_queue_scheduled_executions_on_queue_name"
     t.index ["scheduled_at", "priority", "job_id"], name: "index_solid_queue_dispatch_all"
   end