Common SQLite Mistakes Developers Make (and How to Avoid Them)

SQLite is an excellent choice for lightweight, embedded databases. It’s easy to set up, requires no separate server, and works seamlessly across various platforms. However, despite its simplicity, developers—especially those new to SQLite—often make mistakes that can lead to performance issues, security vulnerabilities, or even data loss.

I’ve worked with SQLite on numerous projects, and over time, I’ve come across several common pitfalls. In this blog, I’ll share some of the most frequent mistakes developers make when working with SQLite and how to avoid them.

1. Using Default SQLite Settings Without Optimization

One of the biggest mistakes developers make is assuming that SQLite’s default settings are optimized for performance. While SQLite works well out of the box, tuning certain settings can significantly improve efficiency.

How to Avoid This Mistake:

  • Enable Write-Ahead Logging (WAL) Mode:
    By default, SQLite uses rollback journal mode, which can slow down write operations. Switching to WAL mode improves concurrency and performance. sqlCopyEditPRAGMA journal_mode = WAL;
  • Increase Cache Size:
    The default cache size is often too small for high-performance applications. You can increase it using: sqlCopyEditPRAGMA cache_size = 10000;

2. Not Using Indexes Properly

Indexes play a crucial role in query performance. A common mistake is either not using indexes at all or using them incorrectly.

How to Avoid This Mistake:

  • Add Indexes to Frequently Queried Columns: sqlCopyEditCREATE INDEX idx_users_name ON users(name);
  • Avoid Over-Indexing: Adding too many indexes can slow down write operations because every INSERT, UPDATE, or DELETE operation needs to update the indexes.

3. Using SELECT * in Queries

It’s tempting to use SELECT * in queries to retrieve all columns from a table, but this can lead to unnecessary data fetching, reducing performance.

How to Avoid This Mistake:

  • Always Specify the Columns You Need: sqlCopyEditSELECT name, email FROM users WHERE id = 1;
  • Only Fetch What You Use: If you don’t need all the data, don’t retrieve it.

4. Ignoring Transactions for Bulk Operations

SQLite supports transactions, but many developers forget to use them, leading to inefficient write operations.

How to Avoid This Mistake:

  • Wrap Bulk Inserts in a Transaction: sqlCopyEditBEGIN TRANSACTION; INSERT INTO users (name, email) VALUES ('Alice', 'alice@example.com'); INSERT INTO users (name, email) VALUES ('Bob', 'bob@example.com'); COMMIT; Without transactions, each INSERT statement runs separately, causing a significant performance hit.

5. Forgetting to Close Database Connections

In many applications, developers forget to close database connections, leading to memory leaks and performance degradation.

How to Avoid This Mistake:

  • Always Close Connections: If you’re using Python, for example: pythonCopyEditconn = sqlite3.connect('database.db') cursor = conn.cursor() cursor.execute("SELECT * FROM users") conn.close() # Don't forget to close the connection!
  • Use Context Managers (Python-specific best practice): pythonCopyEditwith sqlite3.connect('database.db') as conn: cursor = conn.cursor() cursor.execute("SELECT * FROM users") Using a with statement ensures that the connection is automatically closed.

6. Not Handling Concurrency Properly

SQLite allows multiple readers but only one writer at a time. Many developers assume SQLite supports concurrent writes as seamlessly as MySQL or PostgreSQL, leading to database lock errors.

How to Avoid This Mistake:

  • Use WAL Mode for Better Concurrency: sqlCopyEditPRAGMA journal_mode = WAL;
  • Reduce Locking by Writing Less Frequently: If possible, batch writes instead of making frequent small updates.
  • Use retry Logic: If a write fails due to a locked database, retry after a short delay.

7. Storing Large BLOBs Directly in SQLite

SQLite supports storing binary large objects (BLOBs) such as images and videos, but storing large files directly in the database can slow down queries and increase database size.

How to Avoid This Mistake:

  • Store File Paths Instead of Files: Instead of storing the actual image, store its location on disk. sqlCopyEditINSERT INTO images (image_path) VALUES ('/path/to/image.jpg');
  • Use External Storage Solutions: If you’re handling a large number of media files, consider storing them in cloud storage or a separate file system.

8. Not Backing Up the Database Regularly

Many developers overlook database backups, assuming SQLite’s file-based nature makes it inherently safe. However, corruption, accidental deletions, or system crashes can still cause data loss.

How to Avoid This Mistake:

  • Use SQLite’s Built-in Backup Feature: sqlCopyEdit.backup my_database_backup.db
  • Automate Backups: Set up a cron job or scheduled task to create regular backups.

9. Ignoring Security Best Practices

SQLite doesn’t have built-in authentication, meaning it’s up to the developer to secure the database. Many developers leave their database files exposed.

How to Avoid This Mistake:

  • Set Proper File Permissions: shCopyEditchmod 600 database.db
  • Encrypt the Database Using SQLCipher: sqlCopyEditPRAGMA key = 'super_secure_password';
  • Never Store the Database in a Publicly Accessible Directory: If your SQLite file is inside your web server’s root, an attacker could download it.

10. Failing to Keep SQLite Updated

SQLite is actively maintained with frequent security patches and performance improvements, but many developers stick to older versions.

How to Avoid This Mistake:

  • Check for updates regularly on sqlite.org.
  • Use a package manager to keep SQLite updated: shCopyEditsudo apt update && sudo apt upgrade sqlite3

Final Thoughts

SQLite is a powerful and efficient database engine, but like any technology, it requires careful handling. By avoiding these common mistakes—whether it’s optimizing queries, using transactions, or securing your database—you can ensure that your SQLite-powered applications are fast, secure, and reliable.

If you’ve encountered any of these mistakes or have additional tips, feel free to share in the comments. Let’s learn from each other and make better use of SQLite!