PGSimCity is an interactive web-based simulation created by Nikolay Samokhvalov that visualizes PostgreSQL internals in real time. The tool models core database processes including query parsing, planning, execution, buffer management, WAL (Write-Ahead Logging), and vacuum operations. Users can observe how data flows through the system, how locks and transactions behave, and how background workers maintain database health.

The simulation renders each component as animated blocks and flows, making abstract concepts tangible. It covers memory structures like shared buffers and work memory, showing how pages are read, dirtied, and flushed. Transaction isolation levels, deadlock detection, and checkpoint mechanics are also illustrated.

PGSimCity serves as an educational resource for developers, DBAs, and students seeking to deepen their understanding of PostgreSQL architecture without reading source code. The project is open source and runs entirely in the browser, requiring no installation.