Preview environments are temporary deployment environments created for each pull request, offering major advantages over traditional shared staging environments. While platforms like Vercel (paid) and Coolify (open-source) solve application deployment, the database remains the bottleneck. Teams typically compromise: sharing one database (causing conflicts), deploying small test databases (lacking realistic data), or cloning large production databases (taking hours and costing heavily). DBLab 4.0's database branching solves this with O(1) economics, spinning up isolated production-scale Postgres clones in seconds for cost-effective full-stack previews.