diff --git a/ref-test/app/models/dataset.py b/ref-test/app/models/dataset.py
index dc870f5..6a22da3 100644
--- a/ref-test/app/models/dataset.py
+++ b/ref-test/app/models/dataset.py
@@ -14,8 +14,7 @@ from pathlib import Path
 from uuid import uuid4
 
 class Dataset(db.Model):
-
-    id = db.Column(db.String(36), primary_key=True)
+    id = db.Column(db.String(36), index=True, primary_key=True)
     name = db.Column(db.String(128), nullable=False)
     tests = db.relationship('Test', backref='dataset')
     creator_id = db.Column(db.String(36), db.ForeignKey('user.id'))
diff --git a/ref-test/app/models/entry.py b/ref-test/app/models/entry.py
index b9d07da..217f0b6 100644
--- a/ref-test/app/models/entry.py
+++ b/ref-test/app/models/entry.py
@@ -11,16 +11,15 @@ from datetime import datetime, timedelta
 from uuid import uuid4
 
 class Entry(db.Model):
-
-    id = db.Column(db.String(36), primary_key=True)
+    id = db.Column(db.String(36), index=True, primary_key=True)
     first_name = db.Column(db.String(128), nullable=False)
     surname = db.Column(db.String(128), nullable=False)
     email = db.Column(db.String(128), nullable=False)
     club = db.Column(db.String(128), nullable=True)
     test_id = db.Column(db.String(36), db.ForeignKey('test.id'))
     user_code = db.Column(db.String(6), nullable=True)
-    start_time = db.Column(db.DateTime, nullable=True)
-    end_time = db.Column(db.DateTime, nullable=True)
+    start_time = db.Column(db.DateTime, index=True, nullable=True)
+    end_time = db.Column(db.DateTime, index=True, nullable=True)
     status = db.Column(db.String(16), nullable=True)
     valid = db.Column(db.Boolean, default=True, nullable=True)
     answers = db.Column(MutableJson, nullable=True)
diff --git a/ref-test/app/models/test.py b/ref-test/app/models/test.py
index 1bdc160..7bf5e5c 100644
--- a/ref-test/app/models/test.py
+++ b/ref-test/app/models/test.py
@@ -9,10 +9,9 @@ import secrets
 from uuid import uuid4
 
 class Test(db.Model):
-    
-    id = db.Column(db.String(36), primary_key=True)
-    code = db.Column(db.String(36), nullable=False)
-    start_date = db.Column(db.DateTime, nullable=True)
+    id = db.Column(db.String(36), index=True, primary_key=True)
+    code = db.Column(db.String(36), index=True, nullable=False)
+    start_date = db.Column(db.DateTime, index=True, nullable=True)
     end_date = db.Column(db.DateTime, nullable=True)
     time_limit = db.Column(db.Integer, nullable=True)
     creator_id = db.Column(db.String(36), db.ForeignKey('user.id'))
diff --git a/ref-test/app/models/user.py b/ref-test/app/models/user.py
index 8101e97..d8d55e5 100644
--- a/ref-test/app/models/user.py
+++ b/ref-test/app/models/user.py
@@ -11,11 +11,11 @@ from werkzeug.security import check_password_hash, generate_password_hash
 import secrets
 from uuid import uuid4
 class User(UserMixin, db.Model):
-    id = db.Column(db.String(36), primary_key=True)
+    id = db.Column(db.String(36), index=True, primary_key=True)
     username = db.Column(db.String(128), nullable=False)
     password = db.Column(db.String(128), nullable=False)
     email = db.Column(db.String(128), nullable=False)
-    reset_token = db.Column(db.String(20), nullable=True)
+    reset_token = db.Column(db.String(20), index=True, nullable=True)
     verification_token = db.Column(db.String(20), nullable=True)
     tests = db.relationship('Test', backref='creator')
     datasets = db.relationship('Dataset', backref='creator')