PlanetScale - MySQL That Actually Scales Without The Pain

PlanetScale is a managed MySQL database that runs on Vitess - the open-source database tech that YouTube uses to keep their shit from falling over when millions of people upload cat videos simultaneously. It was started by engineers who got tired of being woken up at 3am because MySQL couldn't handle traffic spikes.

Core Technology: Vitess Architecture

The key thing is Vitess - Google's open-source solution for when MySQL needs to handle more traffic than a single server can manage. YouTube built this because their MySQL database was about to explode from all the video uploads. Instead of rewriting their entire app, they made MySQL pretend to be one giant database while actually running on hundreds of servers behind the scenes.

Here's how Vitess works under the hood:

VTGate (Query Router): This is the thing your app talks to. It looks like regular MySQL to your application, but behind the scenes it's figuring out which actual MySQL server has your data and sending queries there. If one server dies, VTGate just routes around it. I spent way too much time reading Vitess docs to understand this part.

VTTablet (MySQL Mediator): This sits in front of each MySQL instance and handles connection pooling. Regular MySQL hits the wall pretty fast with concurrent connections (default limit is 151, but you can crank it higher until your server runs out of memory). VTTablet can handle thousands because it actually reuses connections instead of creating new ones like an idiot.

MySQL Instances: Your actual data lives on regular MySQL servers. PlanetScale sets up one primary for writes and two replicas for reads. When the primary dies (and it will), one replica gets promoted automatically.

What PlanetScale Actually Does For You

PlanetScale handles the database operations that usually require a dedicated database admin. No more planning server capacity, managing backups, or applying security patches. You just use the database and they handle the infrastructure headaches.

The pricing is consumption-based, which is great when you're starting out (free tier is permanent, not like AWS's 12-month bait-and-switch), but can get expensive fast when you scale. Learned this the hard way when our analytics queries started costing us $200/month. More on that nightmare in the pricing section below.

Database Branching (The Killer Feature)

The best part of PlanetScale is database branching - think Git for your database schema. You can create a branch, fuck around with the schema, test it, then merge back to production without downtime.

This is huge because normally changing a database schema means:

1. Schedule downtime at 2am
2. Cross your fingers the migration works
3. Get paged at 2:30am when something breaks
4. Spend 3 hours rolling back

With PlanetScale, you just merge the branch and Vitess handles the migration behind the scenes. Been using this for about a year now - it's saved our team probably 20+ hours of coordination bullshit and late-night stress deployments.

Performance Reality Check

PlanetScale performs well because Vitess was battle-tested at YouTube scale. Will your app be faster? Probably. Will it be the fastest database ever? No.

The real performance benefit comes from not having your database fall over when traffic spikes. Instead of your MySQL server dying under load, Vitess spreads queries across multiple servers automatically. Your app stays up, customers stay happy, you don't get woken up at 3am by alerts.

Database Branching - The Good and The Ugly

Database branching is legitimately game-changing if you're used to MySQL migrations that lock up your tables. You create a branch (just the schema, not data), test your changes, then merge back without downtime.

The good: No more 3am maintenance windows for schema changes. No more praying your ALTER TABLE doesn't kill production.

The ugly: Branches only copy schema, not data. So if you're testing a migration that depends on specific data conditions, you're still fucked. Also, if your migration breaks something subtle, you won't know until it hits production data.

The gotcha: Schema rollbacks aren't always possible. If you add a column, fill it with data, then want to rollback - congrats, you just lost data. Vitess can't magically undo destructive changes.

Vector Storage (Just Went GA, Haven't Tried It Yet)

PlanetScale just launched vector storage GA in March 2025 for AI workloads. You can supposedly store embeddings next to your regular data instead of managing a separate Pinecone/Weaviate/whatever.

Why it sounds appealing: One less database to manage, no ETL between your app data and vectors.

Why the pricing looks scary: Haven't tried it yet, but based on their consumption pricing model, running vector similarity searches could make your AWS bill look reasonable. Vector storage is compute-intensive and they charge for every row read - do the math on scanning millions of embeddings. One teammate ran a similarity search on 500k embeddings and got slapped with a $180 charge for what should've been a $5 query.

Horizontal Sharding (When You Get Big)

Sharding is where PlanetScale actually shines. Most companies try to shard their MySQL database and end up with a maintenance nightmare. PlanetScale automates the hard parts through Vitess.

What it handles automatically:

• Splitting data across multiple MySQL servers
• Routing queries to the right shard
• Rebalancing when shards get uneven
• Adding new shards when you outgrow existing ones

What you still need to think about: Your sharding key better be good from day one. If you choose wrong (like sharding by company when most of your data is in one big company), you're going to have hot shards and there's no magic fix.

Performance Insights (Actually Useful)

PlanetScale Insights shows you which queries are slow, which indexes are missing, and where your app is wasting database resources. It's better than most homegrown monitoring.

What you get:

• Query performance broken down by execution time
• Suggestions for missing indexes (though you should know your queries)
• Connection pool stats so you know if you're hitting limits

What you don't get: Deep query plan analysis like you'd get from running EXPLAIN in regular MySQL. If you need to debug complex query optimization, you'll still need to dig into the raw MySQL.

The MySQL Compatibility Trap

Here's the part PlanetScale doesn't advertise prominently: Vitess doesn't support all MySQL features. Foreign keys? Nope. Triggers? Nope. Stored procedures? Nope.

If your app relies on:

• Foreign key constraints for data integrity
• Database triggers for business logic
• Stored procedures for complex operations
• FULLTEXT indexes for search

You're going to have a bad time migrating. You'll need to rewrite parts of your application to handle these constraints at the app level. We spent 2 weeks rewriting our order validation logic after finding out PlanetScale doesn't give a shit about our foreign key constraints - orders were getting created with invalid customer IDs and we didn't catch it until production blew up.

Security and Compliance (Standard Enterprise Stuff)

PlanetScale has the compliance certifications you need:

• SOC 2 Type 2 (security auditing)
• PCI DSS (payment processing)
• HIPAA BAA (healthcare data)

The security stuff is standard enterprise bullshit, but they actually do it right - encryption everywhere, proper access controls, audit logs that work when compliance asks for them.

API and Tooling (Pretty Good)

The PlanetScale API and CLI are well-designed. You can automate database operations, integrate with CI/CD, and manage everything programmatically.

Works well with:

• GitHub Actions for automated deployments
• Terraform for infrastructure as code
• Standard MySQL tools for local development

The CLI is particularly nice - feels like working with Git but for database schema changes.