perf: remove redundant COUNT query and use bulk insert for CSV imports

app/routes/data.py

@@ -17,16 +17,17 @@ def manage_data():
             try:
                 csv_data = csv.reader(StringIO(file.read().decode('utf-8')))
                 next(csv_data)  # Skip the header row
+                readings_to_add = []
                 for row in csv_data:
                     timestamp, systolic, diastolic, heart_rate = row
-                    reading = Reading(
+                    readings_to_add.append(Reading(
                         user_id=current_user.id,
                         timestamp=datetime.strptime(timestamp, '%Y-%m-%d %H:%M:%S'),
                         systolic=int(systolic),
                         diastolic=int(diastolic),
                         heart_rate=int(heart_rate),
-                    )
-                    db.session.add(reading)
+                    ))
+                db.session.bulk_save_objects(readings_to_add)
                 db.session.commit()
                 flash('Data imported successfully!', 'success')
             except Exception as e:

app/routes/main.py

@@ -288,12 +288,9 @@ def prepare_graph_data(readings):
 
 def calculate_progress_badges(user_id, user_tz):
     """Generate badges based on user activity and milestones using optimized queries."""
-    total_readings = Reading.query.filter_by(user_id=user_id).count()
-    if total_readings == 0:
-        return []
-
-    # Fetch only timestamps (highly optimized compared to fetching full objects)
+    # Fetch only timestamps (index-only scan on the composite index)
     timestamps = db.session.query(Reading.timestamp).filter(Reading.user_id == user_id).order_by(Reading.timestamp.desc()).all()
+    total_readings = len(timestamps)
     return _compute_badges(total_readings, timestamps, user_tz)
 
 def _compute_badges(total_readings, timestamps, user_tz, now_local=None):