Add index to commits on user + timestamp

Based on another pg_analyze recommendation

db/migrate/20250609144356_add_index_to_commits_user_id_created_at.rb

@@ -0,0 +1,7 @@
+class AddIndexToCommitsUserIdCreatedAt < ActiveRecord::Migration[8.0]
+  disable_ddl_transaction!
+
+  def change
+    add_index :commits, [:user_id, :created_at], algorithm: :concurrently
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_06_09_143856) do
+ActiveRecord::Schema[8.0].define(version: 2025_06_09_144356) do
   create_schema "pganalyze"
 
   # These are extensions that must be enabled in order to support this database
@@ -79,6 +79,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_06_09_143856) do
     t.datetime "updated_at", null: false
     t.bigint "repository_id"
     t.index ["repository_id"], name: "index_commits_on_repository_id"
+    t.index ["user_id", "created_at"], name: "index_commits_on_user_id_and_created_at"
     t.index ["user_id"], name: "index_commits_on_user_id"
   end