The issue you're experiencing could be related to how your application handles the upload process and the database transactions. Here are a few steps you can take to diagnose and resolve the issue:

1. Transaction Management

Ensure that the entire upload process is wrapped in a database transaction. This way, if the upload is interrupted or fails, the transaction can be rolled back, preventing partial uploads.

import MySQLdb

def upload_data(file_path):
    connection = MySQLdb.connect(user='user', password='passwd', host='localhost', database='database')
    cursor = connection.cursor()

    try:
        # Start a transaction
        connection.begin()
        
        # Your code to read the Excel file and insert data into the database
        for row in read_excel(file_path):
            cursor.execute("INSERT INTO table_name (column1, column2) VALUES (%s, %s)", (row['column1'], row['column2']))
        
        # Commit the transaction
        connection.commit()
    except Exception as e:
        # Rollback the transaction if there is an error
        connection.rollback()
        print(f"Error: {e}")
    finally:
        cursor.close()
        connection.close()

2. Check for Existing Records

Before inserting a new record, check if it already exists in the database. You can do this by querying the database to see if a record with the same unique fields already exists.

def upload_data(file_path):
    connection = MySQLdb.connect(user='user', password='passwd', host='localhost', database='database')
    cursor = connection.cursor()

    try:
        connection.begin()
        
        for row in read_excel(file_path):
            cursor.execute("SELECT COUNT(*) FROM table_name WHERE unique_field=%s", (row['unique_field'],))
            if cursor.fetchone()[0] == 0:
                cursor.execute("INSERT INTO table_name (unique_field, column2) VALUES (%s, %s)", (row['unique_field'], row['column2']))
        
        connection.commit()
    except Exception as e:
        connection.rollback()
        print(f"Error: {e}")
    finally:
        cursor.close()
        connection.close()

3. Implement Idempotent Uploads

Generate a unique identifier for each upload session. Store this identifier in the database along with each row of data. If the upload is interrupted and restarted, use the same identifier to check if a row has already been uploaded.

4. Clean Up Partial Uploads

If an upload is interrupted, clean up any partial uploads before starting a new one. This can be done by deleting rows associated with the interrupted upload session.

def upload_data(file_path, session_id):
    connection = MySQLdb.connect(user='user', password='passwd', host='localhost', database='database')
    cursor = connection.cursor()

    try:
        connection.begin()
        
        # Clean up previous partial uploads for the session
        cursor.execute("DELETE FROM table_name WHERE session_id=%s", (session_id,))
        
        for row in read_excel(file_path):
            cursor.execute("INSERT INTO table_name (session_id, unique_field, column2) VALUES (%s, %s, %s)", (session_id, row['unique_field'], row['column2']))
        
        connection.commit()
    except Exception as e:
        connection.rollback()
        print(f"Error: {e}")
    finally:
        cursor.close()
        connection.close()

5. Use Temporary Tables

During the upload process, insert data into a temporary table. Once the upload is complete, move the data from the temporary table to the main table in a single transaction.

6. Handle Client-Side Aborts

Ensure that your server is aware of client-side aborts and can handle them gracefully. This might involve setting up proper signal handling or using frameworks that support long-running requests and can detect client disconnections.

7. Unique Constraints

Ensure that your database schema has proper unique constraints and indexes to prevent duplicate entries at the database level. Even if your application logic fails, the database constraints should prevent duplicates.

By combining these approaches, you can make your upload process more robust and prevent duplicate entries in your database.