add changes

backend/models/QuizSession.js

@@ -164,6 +164,32 @@ module.exports = (sequelize) => {
     tableName: 'quiz_sessions',
     timestamps: true,
     underscored: true,
+    indexes: [
+      {
+        fields: ['user_id']
+      },
+      {
+        fields: ['guest_session_id']
+      },
+      {
+        fields: ['category_id']
+      },
+      {
+        fields: ['status']
+      },
+      {
+        fields: ['created_at']
+      },
+      {
+        fields: ['user_id', 'created_at']
+      },
+      {
+        fields: ['guest_session_id', 'created_at']
+      },
+      {
+        fields: ['category_id', 'status']
+      }
+    ],
     hooks: {
       beforeValidate: (session) => {
         // Generate UUID if not provided