Convex vs. Traditional Databases: The Real-Time Advantage
We switched to Convex for all new projects about 18 months ago. The switch wasn't obvious, but it eliminates categories of problems that slow down MVP development.
October 29, 2024 8 min read
# Convex vs. Traditional Databases: The Real-Time Advantage
Slug: convex-vs-traditional-databases
Date: 2024-10-29
Tag: Tech Stack
Meta Description: Why NextBuild switched to Convex for new projects. Real-time sync, TypeScript integration, and the trade-offs compared to PostgreSQL and traditional databases.
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We switched to Convex for all new projects about 18 months ago. Before that, we used PostgreSQL with Prisma, occasional MongoDB, and Supabase for real-time needs.
The switch wasn't obvious. Convex is newer, less battle-tested, and creates vendor lock-in. We made the change anyway because it eliminates categories of problems that slow down MVP development.
This post explains what Convex actually is, why real-time matters more than most teams realize, and when you should—or shouldn't—follow our approach.
What Convex Actually Is
Convex is a backend-as-a-service that combines database, real-time sync, serverless functions, and file storage into one platform. Think of it as Firebase rebuilt with TypeScript and modern developer experience as priorities.
The core mental model:
Everything is a function. Queries read data. Mutations change data. Actions call external APIs. All functions run on Convex's servers.
Real-time is default. When data changes, every connected client with a relevant query gets the update. You don't implement this—it happens automatically.
. Schema definitions, function arguments, return types—all TypeScript with full inference.
When createTask runs, the tasks list updates automatically for all connected clients. No WebSocket setup. No cache invalidation logic. No optimistic update code.
Why Real-Time Changes Everything
Most MVP teams think of real-time as a nice-to-have feature for chat apps. That undersells the impact.
Real-time sync changes how your entire application feels. Every interaction provides immediate feedback. Multiple team members can work simultaneously without refresh cycles. Dashboards stay current without polling.
The Traditional Approach
With a traditional database and REST API, showing updated data requires:
User takes an action
API call sends the change to the server
Server updates the database
API returns success
Frontend either:
- Re-fetches the entire list (simple but slow)
- Manually updates local state (error-prone)
- Uses optimistic updates (complex to implement correctly)
Other users see stale data until they refresh
This pattern is fine for many applications. It's been the standard for years. But it requires managing consistency between server state and client state—a constant source of subtle bugs.
The Convex Approach
With Convex:
User takes an action
Mutation sends the change to Convex
Convex updates the database
All connected clients with relevant queries receive the update automatically
React re-renders with new data
No manual re-fetching. No optimistic update code. No cache invalidation strategy.
The code for a collaborative todo list with real-time sync is essentially the same as a single-user todo list. You get multiplayer functionality without multiplayer complexity.
Even for single-user applications, the automatic state synchronization reduces bugs. You never show stale data because there's one source of truth that stays synchronized.
The TypeScript Integration
TypeScript with traditional backends often feels bolted-on. You define types for your API layer, then hope they match your database schema, then maintain synchronization as things change.
Convex inverts this. Your schema definition generates types that flow through to your frontend:
Convex isn't a free upgrade. There are real trade-offs.
SQL Knowledge Doesn't Transfer
If your team has years of PostgreSQL experience, that expertise has limited value in Convex. The query language is JavaScript-based, not SQL. Complex joins work differently. There's no raw SQL escape hatch.
Teams comfortable with:
sql
SELECT p.name, COUNT(t.id) as task_count
FROM projects p
LEFT JOIN tasks t ON t.project_id = p.id
GROUP BY p.id
ORDER BY task_count DESC
The Convex version is more verbose but equally type-safe. Whether that's a worthwhile trade-off depends on your team.
Vendor Lock-in Is Real
Convex runs on Convex's infrastructure. You can't export your functions and run them on AWS. If Convex raises prices, has reliability issues, or shuts down, migration is significant work.
For enterprise products with on-premises requirements, this is a non-starter. For MVPs focused on speed to market, the development velocity advantage outweighs the lock-in risk.
Our reasoning: if the MVP fails, lock-in doesn't matter. If it succeeds, you'll have resources to address infrastructure decisions.
Ecosystem Is Smaller
PostgreSQL has decades of tooling, tutorials, and specialized knowledge. Convex has been in production for about three years. When you hit an unusual problem, fewer people have solved it before you.
This is improving. Convex's documentation is excellent, their Discord community is responsive, and the product is maturing. But if you need a specific PostgreSQL extension or battle-tested migration tooling, it doesn't exist yet.
Pricing at Scale
Convex's free tier is generous for MVPs. Paid tiers are reasonable for growing products. At very high scale—millions of database operations daily—the economics change.
For most startups, this is a problem you want to have. If your data volume justifies self-hosted PostgreSQL, you're succeeding.
Comparison to Supabase
Supabase is the most common alternative we're asked about. Both are backend-as-a-service platforms, but they take different approaches.
Supabase Approach
PostgreSQL at its core: Full SQL power with all PostgreSQL features
Real-time via Realtime Server: Opt-in subscriptions to table changes
Auth, Storage, Edge Functions: Complete platform like Convex
More flexible hosting: Can self-host the entire stack
Convex Approach
Custom database engine: Designed specifically for real-time sync
Real-time by default: Every query automatically subscribes
TypeScript-native: Types flow through the entire stack
You need PostgreSQL-specific features (PostGIS, advanced queries)
Self-hosting is a requirement
You're integrating with existing PostgreSQL systems
Use Convex when:
You want the simplest real-time development
TypeScript-first development is a priority
Your team is comfortable learning new paradigms
Speed of development matters more than ecosystem maturity
We switched to Convex because the real-time defaults and TypeScript integration accelerate MVP development. Teams with different priorities might reasonably choose Supabase.
When to Avoid Convex
Some projects shouldn't use Convex:
Heavy Analytics Workloads
If your product involves complex analytical queries—aggregations across millions of rows, time-series analysis, data warehousing patterns—Convex isn't the right tool. Use a specialized analytics database.
Regulatory Requirements for Data Location
Some industries require data to reside in specific geographic regions or on-premises infrastructure. Convex's hosted model doesn't support this currently.
Existing Database Migration
If you're rebuilding an existing product with an established PostgreSQL database, migrating to Convex might not be worth the effort. Convex shines for greenfield projects.
Team Expertise Heavily in SQL
If your entire team thinks in SQL and the project timeline doesn't allow for learning a new paradigm, use what you know. Productivity matters more than theoretical benefits.
For more complex background processing, Convex supports delayed actions and retries.
Migration Path
If you decide Convex isn't working, what's the migration path?
Export Options
Convex provides data export to JSON. You can snapshot your entire database for migration to another system.
Rewriting Functions
The harder part is rewriting your backend logic. Convex functions need to become API routes (Next.js) or separate services (Node.js). The logic is portable; the infrastructure integration isn't.
Realistic Timeline
Migrating a moderate-sized application from Convex to PostgreSQL + custom backend would take 2-4 weeks of development work. That's significant but not catastrophic.
Convex is our default backend for new projects because:
Real-time by default: No WebSocket setup or cache invalidation code
TypeScript throughout: End-to-end type safety without maintenance
Faster development: Less infrastructure code, more product code
Simpler architecture: One platform instead of database + backend + file storage
The trade-offs are real:
Vendor lock-in: Can't self-host or run on your own infrastructure
Newer ecosystem: Fewer tutorials, tools, and specialized knowledge
SQL doesn't apply: Teams need to learn new patterns
Scale economics: Might not be cost-optimal at very high volumes
For MVPs and early-stage products, the development speed advantage outweighs these concerns. You can always migrate later—if you're successful enough to need different infrastructure, that's a good problem.
For teams with strong PostgreSQL expertise, existing database investments, or specific hosting requirements, Supabase or traditional databases remain solid choices.
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At NextBuild, we build MVPs with Convex, Next.js, and TypeScript. If you're evaluating backend options for your startup, let's discuss your requirements.
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