--- title: How PGSimCity Turns PostgreSQL Complexity Into a Virtual... description: Nikolay Samokhvalov released PGSimCity, an open-source browser-based 3D visualisation that maps PostgreSQL 18 cluster internals onto a virtual city, letting... canonical: https://daily.dev/posts/how-pgsimcity-turns-postgresql-complexity-into-a-virtual-city-3d-simulation-hujsavfey twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: How PGSimCity Turns PostgreSQL Complexity Into a Virtual City 3D Simulation | daily.dev og:description: Nikolay Samokhvalov released PGSimCity, an open-source browser-based 3D visualisation that maps PostgreSQL 18 cluster internals onto a virtual city, letting... og:url: https://daily.dev/posts/how-pgsimcity-turns-postgresql-complexity-into-a-virtual-city-3d-simulation-hujsavfey og:image: https://api.daily.dev/og/posts/HUjsAvFEY.png og:image:alt: How PGSimCity Turns PostgreSQL Complexity Into a Virtual City 3D Simulation og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # How PGSimCity Turns PostgreSQL Complexity Into a Virtual City 3D Simulation **[InfoQ](https://daily.dev/sources/infoq)** · 3 min read · 0 upvotes · 0 comments ## Summary Nikolay Samokhvalov released PGSimCity, an open-source browser-based 3D visualisation that maps PostgreSQL 18 cluster internals onto a virtual city, letting backend developers, SREs, and database architects explore concepts like shared_buffers, WAL, autovacuum, and checkpoint storms interactively. Built with three.js for rendering and isolated TypeScript state machines for simulation logic, it uses PGlite to run a real WebAssembly-compiled Postgres instance client-side. Users can trigger pathologies such as small shared_buffers causing clock-sweep eviction, restricted work_mem causing temp file spills, and long transactions starving autovacuum. The project sparked Hacker News discussion on AI-assisted architecture visualisation, with the prototype built via heavy LLM prompting refined against Postgres source, and inspired a ClickHouse spin-off called CHSimCity. It's Apache-2.0 licensed and open for contributions, with a roadmap covering statement-pooling visualisation and alignment with io_combine_limit and effective_io_concurrency. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What is PGSimCity and how does it visualize PostgreSQL internals? PGSimCity is an open-source browser-based 3D simulation that maps PostgreSQL 18 cluster mechanics onto a virtual city, with districts for the Postmaster, shared_buffers, WAL, and maintenance workers. It runs entirely client-side using three.js for rendering, isolated TypeScript state machines for simulation logic, and PGlite to execute real WebAssembly-compiled Postgres in the browser. _Developers digging into database internals can follow tools like this via daily.dev alongside deeper PostgreSQL resources._ ### How can I simulate buffer eviction problems or work_mem spills in PostgreSQL without a real cluster? Setting shared_buffers to 16 MB in PGSimCity triggers clock-sweep eviction races where backends must write dirty victim pages before reading new data, and restricting work_mem causes Sort and HashAggregate nodes to spill temporary files into base/pgsql_tmp, both visualized interactively without needing a live PostgreSQL instance. _Engineers troubleshooting memory tuning issues can track hands-on PostgreSQL tooling like this through daily.dev._ ### What causes checkpoint storms and table bloat in PostgreSQL? Long-running transactions depress the xmin horizon, starving autovacuum and causing table bloat, while heavy write bursts trigger checkpoint storms that flood pg_wal with full-page writes once the max_wal_size divided by one plus checkpoint_completion_target threshold is crossed. PGSimCity lets engineers trigger and observe these pathologies interactively to understand engine failure modes. _SREs diagnosing production bloat and checkpoint issues can keep tabs on PostgreSQL deep dives via daily.dev._ --- Tags: [#open-source](https://daily.dev/tags/open-source), [#postgresql](https://daily.dev/tags/postgresql), [#data-visualization](https://daily.dev/tags/data-visualization), [#threejs](https://daily.dev/tags/threejs) [View this post on daily.dev](https://daily.dev/posts/how-pgsimcity-turns-postgresql-complexity-into-a-virtual-city-3d-simulation-hujsavfey) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"How PGSimCity Turns PostgreSQL Complexity Into a Virtual City 3D Simulation","url":"https://daily.dev/posts/how-pgsimcity-turns-postgresql-complexity-into-a-virtual-city-3d-simulation-hujsavfey","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/how-pgsimcity-turns-postgresql-complexity-into-a-virtual-city-3d-simulation-hujsavfey"},"datePublished":"2026-08-16T05:06:04.536Z","dateModified":"2026-09-14T08:57:05.261Z","description":"Nikolay Samokhvalov released PGSimCity, an open-source browser-based 3D visualisation that maps PostgreSQL 18 cluster internals onto a virtual city, letting...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/85e80c27fb63fec74716828c0db48d92?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/85e80c27fb63fec74716828c0db48d92?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"InfoQ","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"InfoQ","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/afc3bced3e1e4b188dd9127017a60e0c","url":"https://daily.dev/sources/infoq"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/how-pgsimcity-turns-postgresql-complexity-into-a-virtual-city-3d-simulation-hujsavfey","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"open-source,postgresql,data-visualization,threejs","timeRequired":"PT3M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"InfoQ","item":"https://daily.dev/sources/infoq"},{"@type":"ListItem","position":3,"name":"How PGSimCity Turns PostgreSQL Complexity Into a Virtual City 3D Simulation"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/how-pgsimcity-turns-postgresql-complexity-into-a-virtual-city-3d-simulation-hujsavfey#faq","mainEntity":[{"@type":"Question","name":"What is PGSimCity and how does it visualize PostgreSQL internals?","acceptedAnswer":{"@type":"Answer","text":"PGSimCity is an open-source browser-based 3D simulation that maps PostgreSQL 18 cluster mechanics onto a virtual city, with districts for the Postmaster, shared_buffers, WAL, and maintenance workers. 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