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Automating Database Schema Changes Safely With Feature Flags


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Welcome to a journey through the dynamic world of database schema changes. If you’re in software development, you know how crucial yet challenging these changes can be. They’re like the gears in a clock – essential for the right timing but complex to handle. Now, imagine having a tool that not only manages these changes smoothly but also does it with precision and safety. That’s where feature flags come into play.

In this blog post, I’ll guide you through automating database schema changes safely using feature flags. You might wonder, “Why feature flags?” They’re not just for UI changes or beta features anymore. When it comes to database schemas, especially with a robust system like Postgres, feature flags can be a game-changer. They offer a controlled environment where you can introduce, test, and roll out changes without disrupting the system.

So, buckle up! You’re about to discover how to make your database schema changes more efficient, less risky, and surprisingly straightforward. Let’s dive in and explore this innovative approach that’s reshaping how developers handle database transformations.

Understanding Database Schema Changes

Navigating the world of database schema changes can sometimes feel like walking through a maze. It’s essential, but the complexity can be daunting. Let’s break it down. At its core, a database schema is like the blueprint of your database. It defines the structure, the tables, and the relationships – essentially, how your data is organized and managed.

Now, think about why changes to this schema are necessary. Your application evolves, new features get added, and the existing database structure suddenly doesn’t fit the bill anymore. That’s where schema changes come in. They’re all about adapting and evolving your database to meet new requirements.

But here’s the catch: changing a database schema is like performing surgery on your database. It’s delicate. One wrong move, and you could end up with data loss, downtime, or performance issues. That’s why automating these changes, especially in a robust system like Postgres, isn’t just a convenience; it’s a necessity.

You might have experienced the challenges firsthand. Maybe you’ve dealt with the downtime caused by a direct change in the production database, or perhaps you’ve had to roll back a change that didn’t go as planned. These are common hurdles in the schema change process.

So, how do you make these changes without turning your database into a house of cards? That’s where feature flags come into the picture, offering a safety net. Using a platform like Split, you can introduce changes in a controlled manner, test them thoroughly, and ensure they’re solid before going live.

In the following sections, you’ll see how feature flags can transform how you handle database schema changes, making the process more manageable, less risky, and surprisingly smooth. Stay tuned as you’re about to learn some practical steps to master this approach.

Introduction to Feature Flags

Let’s talk about feature flags (also known as feature toggles or feature gates). You might already be familiar with them, especially if you’ve dabbled in controlling user access to certain application features. But when it comes to database schema changes, feature flags aren’t just about user experience; they’re about control, safety, and flexibility.

Imagine you have a switch that lets you toggle new features or changes on and off without having to redeploy your entire application. That’s what a feature flag does. It separates code deployment from feature release, giving you the power to test new features in your live environment without exposing them to all users.

Now, apply this concept to database schema changes. You’re looking at a powerful tool to help you manage these changes more effectively. With feature flags, you can roll out a new schema change to a small subset of users or environments, test it thoroughly, and then gradually increase its exposure. All this while the rest of your users continue to interact with the stable version of your database.

Using Split for feature flags in this context brings an added layer of sophistication. It’s not just about turning features on and off. Split allows you to target specific segments, perform A/B testing, and gather real-time data on how your changes perform. This level of control and insight is invaluable, especially when dealing with something as critical as database schema changes.

So, as you move forward, remember that feature flags are more than just a safety mechanism. They’re a strategic tool that can help you confidently innovate and evolve your database schemas. In the following sections, you’ll see how to put this tool to use effectively, ensuring your database changes are smooth, controlled, and, most importantly, safe.

Integrating Feature Flags With Database Schema Changes

Let’s dive into how you can integrate feature flags, specifically using Split, with database schema changes in a Postgres environment. The idea here is to create a seamless process that allows you to introduce, test, and implement changes in a controlled and reversible manner.

Step 1: Setting Up Your Environment

First things first, you need to set up your environment. Ensure you have Split integrated into your application. If you’re new to Split, it’s a straightforward process:

const SplitFactory = require('@splitsoftware/splitio').SplitFactory;

const factory = SplitFactory({
  core: {
    authorizationKey: 'YOUR_SPLIT_API_KEY'

const client = factory.client();

This code initializes Split in your application. Replace YOUR_SPLIT_API_KEY with your actual API key from Split.

Step 2: Creating a Feature Flag for Schema Change

Next, create a feature flag in Split for your schema change. Let’s say you’re adding a new column to a table. In Split, you’d create a flag and name it add_new_column_feature.

Step 3: Implementing the Flag in Your Application

Now, implement the flag in your application. Here’s a basic example:

client.on(client.Event.SDK_READY, async function() {
  let treatment = client.getTreatment('add_new_column_feature');

  if (treatment === 'on') {
    // Code to handle new schema
    await updateDatabaseSchema();
  } else {
    // Code to handle old schema
    console.log('Feature flag is off. Using old schema.');

In this snippet, updateDatabaseSchema would be a function you write to modify your Postgres schema, like adding a column.

Step 4: Updating the Database Schema

For the schema update, you’d write a function in your backend. Here’s a simplified example in Node.js using a PostgreSQL client:

async function updateDatabaseSchema() {
  const { Pool } = require('pg');
  const pool = new Pool();

  const query = 'ALTER TABLE your_table ADD COLUMN new_column VARCHAR(255);';

  try {
    await pool.query(query);
    console.log('Column added successfully.');
  } catch (err) {
    console.error('Error executing query', err.stack);

This function adds a new column to your_table. Replace your_table and new_column with your actual table and column names.

Step 5: Testing and Rollout

With everything set up, you can now test your changes. Start by enabling the feature flag for a small group of users or in a specific environment. Monitor the performance and behavior closely. If everything goes smoothly, you can gradually roll out the change to more users.

Step 6: Monitoring and Adjusting

Keep a close eye on your application’s performance and any feedback you receive. The beauty of using feature flags is that if something goes wrong, you can quickly turn off the flag, reverting to the old schema without needing to roll back your entire application.

Integrating feature flags with your database schema changes gives you a powerful tool for managing these changes. It allows you to test in real time, reduce risks, and ensure your database evolves according to your application’s needs. Remember, the key is to start small, test thoroughly, and scale up confidently.

Challenges and Solutions in Automating Schema Changes With Feature Flags

When you’re automating database schema changes with feature flags, it’s like navigating a complex puzzle. Each piece must fit perfectly for the whole picture to come together. Let’s explore some common challenges you might face and how to tackle them effectively.

Challenge 1: Ensuring Consistent State Across Environments

One of the trickiest parts is maintaining a consistent state across different environments (development, staging, production).

Solution: Use environment-specific feature flags in Split. For instance, you can have schema_update_dev, schema_update_staging, and schema_update_prod flags. This way, you can control and test changes separately in each environment.

const envFlag = `schema_update_${process.env.NODE_ENV}`;
const treatment = client.getTreatment(envFlag);

if (treatment === 'on') {
  // Apply schema changes

Challenge 2: Managing Dependencies Between Flags

Sometimes, schema changes depend on each other, creating a dependency chain.

Solution: Implement flag dependencies within your code logic. Before applying a change, check if the dependent flags are active.

const parentFlag = client.getTreatment('parent_schema_change');
const dependentFlag = client.getTreatment('dependent_schema_change');

if (parentFlag === 'on' && dependentFlag === 'on') {
  // Apply dependent schema change

Challenge 3: Handling Long-Running Migrations

Large schema changes can be time-consuming, leading to potential downtime or performance issues.

Solution: Break down large migrations into smaller, incremental changes. Use feature flags to control and monitor each phase. This approach reduces the risk of long-running migrations impacting your system.

Challenge 4: Reverting Changes Safely

What if something goes wrong? You need a quick and safe way to revert changes.

Solution: Always have a rollback plan. Before applying a new schema change, ensure you have a script or mechanism to revert it. With feature flags, you can quickly disable a change but ensure the old schema can handle the current state of your data.

if (treatment === 'off') {
  // Revert to the old schema

Challenge 5: Testing with Realistic Data

Testing schema changes in an environment that doesn’t reflect your production data can lead to unexpected issues.

Solution: Use data masking or anonymization to create a realistic testing environment with production-like data. This approach helps you identify potential issues before they affect your live environment.

Challenge 6: Monitoring and Analyzing Impact

After rolling out a change, you must understand its impact on your system.

Solution: Integrate monitoring tools with your feature flag system. Track performance metrics, error rates, and user feedback related to the schema change. Use this data to make informed decisions about further rollouts or rollbacks.

Automating schema changes with feature flags is a powerful strategy but comes with challenges. By anticipating these issues and preparing solutions, you can confidently navigate these complexities. Remember, the key is to move cautiously, test rigorously, and always have a plan for quick reversals. With these practices in place, you’re well-equipped to handle the dynamic landscape of database schema changes.


So, you’ve journeyed through the intricate process of automating database schema changes using feature flags with Split. It’s a path that combines the technical rigor of database management with the innovative approach of feature flagging. Let’s recap the key takeaways and wrap up this exploration.

Firstly, remember that integrating feature flags into your database schema change process isn’t just about adding a layer of safety. It’s about gaining unprecedented control over how and when changes impact your system. By using Split, you’ve seen how you can roll out changes incrementally, test them in real-world scenarios, and have the flexibility to revert quickly if things don’t go as planned.

Here’s a quick reminder of the core steps:

  • Set up your environment with Split and ensure your database, like Postgres, is ready for changes.
  • Create and implement feature flags for each schema change, allowing you to toggle these changes on and off.
  • Test changes locally and then in a staging environment, gradually increasing exposure and monitoring the impact.
  • Roll out to production cautiously, using Split to control the percentage of traffic exposed to the new schema.
  • Monitor and be ready to revert if needed. Always have a rollback plan in place.
// Example: Toggling a schema change in production
const treatment = client.getTreatment('schema_update_prod');

if (treatment === 'on') {
} else {
  console.log('Feature flag is off. Sticking with the current schema.');

As you move forward, remember that the world of database management and feature flags is ever-evolving. Stay curious and open to new approaches and tools to enhance this process further. The goal is always to ensure that your database changes contribute positively to your application’s stability, performance, and scalability.

In conclusion, automating database schema changes with feature flags is like having a finely tuned instrument in your toolkit. It requires practice, patience, and precision, but the harmony it brings to your deployment process is worth the effort. Keep experimenting, learning, and refining your approach; you’ll find that managing database changes becomes more streamlined and less daunting.

And there you have it! You’re now equipped with the knowledge and strategies to handle database schema changes with confidence and control. Happy coding, and here’s to smooth and successful schema transformations in your future projects!

Switch It On With Split

The Split Feature Data Platform™ gives you the confidence to move fast without breaking things. Set up feature flags and safely deploy to production, controlling who sees which features and when. Connect every flag to contextual data, so you can know if your features are making things better or worse and act without hesitation. Effortlessly conduct feature experiments like A/B tests without slowing down. Whether you’re looking to increase your releases, to decrease your MTTR, or to ignite your dev team without burning them out–Split is both a feature management platform and partnership to revolutionize the way the work gets done. Schedule a demo to learn more.

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