Update PatientSession indexes

This updates the indexes on the patient session model to remove an
unnecessary unique index and add missing indexes on the patient and
session column.

The index on the individual columns should improve performance when
looking up individual patient sessions for a patient or a session,
related to the foreign key added in
b350c8e.

The unique index on `session_id` and `patient_id` is unnecessary as
we already have an index on `patient_id` and `session_id`.

app/models/patient_session.rb

@@ -12,8 +12,9 @@
 #
 # Indexes
 #
+#  index_patient_sessions_on_patient_id                 (patient_id)
 #  index_patient_sessions_on_patient_id_and_session_id  (patient_id,session_id) UNIQUE
-#  index_patient_sessions_on_session_id_and_patient_id  (session_id,patient_id) UNIQUE
+#  index_patient_sessions_on_session_id                 (session_id)
 #
 # Foreign Keys
 #

db/migrate/20241213104730_update_patient_session_indexes.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class UpdatePatientSessionIndexes < ActiveRecord::Migration[8.0]
+  def change
+    remove_index :patient_sessions, %i[session_id patient_id], unique: true
+    add_index :patient_sessions, :patient_id
+    add_index :patient_sessions, :session_id
+  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: 2024_12_13_102755) do
+ActiveRecord::Schema[8.0].define(version: 2024_12_13_104730) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_catalog.plpgsql"
   enable_extension "pg_trgm"
@@ -541,7 +541,8 @@
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.index ["patient_id", "session_id"], name: "index_patient_sessions_on_patient_id_and_session_id", unique: true
-    t.index ["session_id", "patient_id"], name: "index_patient_sessions_on_session_id_and_patient_id", unique: true
+    t.index ["patient_id"], name: "index_patient_sessions_on_patient_id"
+    t.index ["session_id"], name: "index_patient_sessions_on_session_id"
   end
 
   create_table "patients", force: :cascade do |t|

spec/factories/patient_sessions.rb

@@ -12,8 +12,9 @@
 #
 # Indexes
 #
+#  index_patient_sessions_on_patient_id                 (patient_id)
 #  index_patient_sessions_on_patient_id_and_session_id  (patient_id,session_id) UNIQUE
-#  index_patient_sessions_on_session_id_and_patient_id  (session_id,patient_id) UNIQUE
+#  index_patient_sessions_on_session_id                 (session_id)
 #
 # Foreign Keys
 #

spec/models/patient_session_spec.rb

@@ -12,8 +12,9 @@
 #
 # Indexes
 #
+#  index_patient_sessions_on_patient_id                 (patient_id)
 #  index_patient_sessions_on_patient_id_and_session_id  (patient_id,session_id) UNIQUE
-#  index_patient_sessions_on_session_id_and_patient_id  (session_id,patient_id) UNIQUE
+#  index_patient_sessions_on_session_id                 (session_id)
 #
 # Foreign Keys
 #