Does Flask Work With PlanetScale?
Flask and PlanetScale work together seamlessly via standard MySQL drivers, giving you a lightweight Python web framework paired with a modern serverless database.
Quick Facts
How Flask Works With PlanetScale
Flask connects to PlanetScale using standard MySQL libraries like `PyMySQL` or `mysql-connector-python`, typically abstracted through SQLAlchemy via the `Flask-SQLAlchemy` extension. PlanetScale provides a standard MySQL endpoint with SSL/TLS encryption by default, so no special drivers or configuration are needed—just point your connection string at the PlanetScale host. The developer experience is identical to using any hosted MySQL service: define your models in SQLAlchemy, run migrations, and execute queries normally.
PlanetScale's unique features like branching integrate smoothly with Flask's development workflow. You can create feature branches for database schema changes, test them against your Flask app, and merge back to production without downtime. Connection pooling is important here—Flask-SQLAlchemy handles this automatically, but for high-concurrency apps you should configure the pool size appropriately since PlanetScale enforces connection limits. One consideration: PlanetScale doesn't support FOREIGN KEY constraints by default (though this can be enabled), which affects how you structure relationships in SQLAlchemy.
Performance is excellent for typical Flask applications. Query latency depends on geographic proximity to PlanetScale's data centers, but most use cases see sub-50ms response times. SSL connections are enforced, so ensure your driver supports it—this is standard in 2024 and not an issue in practice.
Best Use Cases
Quick Setup
pip install flask flask-sqlalchemy mysql-connector-pythonfrom flask import Flask
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
# Replace USER, PASSWORD, HOST with your PlanetScale credentials
app.config['SQLALCHEMY_DATABASE_URI'] = (
'mysql+mysqlconnector://USER:PASSWORD@HOST/DATABASE?'
'ssl_verify_cert=true&ssl_verify_identity=true'
)
app.config['SQLALCHEMY_ENGINE_OPTIONS'] = {
'pool_size': 5,
'pool_recycle': 3600,
'max_overflow': 10
}
db = SQLAlchemy(app)
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(80))
with app.app_context():
db.create_all()
@app.route('/users')
def get_users():
users = User.query.all()
return [{'id': u.id, 'name': u.name} for u in users]Known Issues & Gotchas
PlanetScale enforces a connection limit; too many pooled connections from Flask will hit the limit and cause 'too many connections' errors
Fix: Set `SQLALCHEMY_ENGINE_OPTIONS = {'pool_size': 5, 'pool_recycle': 3600, 'max_overflow': 10}` in your Flask config, scaled to your deployment size
Foreign key constraints are disabled by default in PlanetScale, which can lead to referential integrity issues if your ORM relies on them
Fix: Enable foreign keys in your PlanetScale database settings if needed, or implement referential integrity checks in your Flask application logic
SSL certificate validation may fail in development if not configured; older PyMySQL versions can be finicky
Fix: Use `ssl_verify_cert=true` and `ssl_verify_identity=true` in your connection string, or upgrade to `mysql-connector-python` which handles this better
PlanetScale's automatic backups don't restore to the same branch; schema changes require careful migration planning
Fix: Use Flask-Migrate (Alembic) for all schema changes and test migrations on a branch before merging to production
Alternatives
- •Django + PostgreSQL (Neon or Railway): Heavier framework with stronger ORM, but more opinionated than Flask
- •Flask + Supabase: Combines Flask with PostgreSQL-backed serverless database with real-time features
- •FastAPI + PlanetScale: More modern async Python framework, better for high-concurrency APIs, same MySQL compatibility
Resources
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