Project ideas from Hacker News discussions.

Making geo joins faster with H3 indexes

📝 Discussion Summary (Click to expand)

Three prevailing themes

# Theme Key quotes
1 Congruency matters for fast joins and analytics “If joins are a critical performance‑sensitive operation, the most important property of a DGGS is congruency.” – jandrewrogers
“Congruency allows for much more efficient join schedules and maximizes selectivity.” – jandrewrogers
“Congruent shards also tend to be more computationally efficient generally, which does add up.” – jandrewrogers
2 H3 is tuned for visualization/aggregates, not for analytic joins “H3 is not congruent it was optimized for visualization, where congruency doesn’t matter, rather than analytical computation.” – jandrewrogers
“H3 is great for doing point geometry aggregates. It shines at that. Not so much geospatial joins though.” – jandrewrogers
“To me, the big selling point of H3 is that once you’re ‘in the H3 system’, many operations don’t need to worry about geometry at all.” – ajfriend
3 Practical solutions often use native spatial indexes or hybrid approaches “We make a set of H3 indexes … and store them in Elasticsearch. Geospatial queries become full‑text search queries.” – cullenking
“Elasticsearch and Opensearch have a built‑in geo_shape type that is a bit more optimal for queries like this.” – jillesvangurp
“Wouldn’t having a spatial index give you most of the performance gains… without needing H3?” – febed

These threads show that while H3 is popular for its simplicity and visualization strengths, its lack of congruency limits join performance, and many practitioners prefer native spatial indexes or hybrid schemes for large‑scale analytic workloads.


🚀 Project Ideas

Generating project ideas…

ConGGS: A Congruent DGGS Library

Summary

  • Provides a fully documented, congruent discrete global grid system (DGGS) that supports efficient spatial joins and concurrent ingestion.
  • Offers a simple API for grid generation, point/polygon conversion, and join operations, outperforming H3/S2 in bandwidth‑bound scenarios.

Details

Key Value
Target Audience GIS developers, data scientists, analytics engineers
Core Feature Congruent grid generation + fast join API
Tech Stack Rust core, C++ bindings, Python & JavaScript wrappers, WebAssembly for browsers
Difficulty High
Monetization Revenue‑ready: subscription + open‑source core

Notes

  • H3 “is not congruent” and S2 “straddles analytics and visualization” – ConGGS fills the gap.
  • Users need “congruency” for scalable joins: “Congruent shards also tend to be more computationally efficient” (jandrewrogers).
  • Potential for discussion: benchmarking against H3/S2, exploring synthetic 3‑space embeddings.

JoinMate: Scalable Spatial Join Service

Summary

  • A cloud‑native service that pre‑indexes large geospatial datasets using a congruent DGGS and exposes a low‑latency join API.
  • Eliminates the need for manual spatial indexing in NoSQL stores and reduces data motion during joins.

Details

Key Value
Target Audience Big‑data teams, analytics engineers, SaaS providers
Core Feature Auto‑indexing, join‑by‑cell API, concurrency‑friendly ingestion
Tech Stack Go, PostgreSQL/PostGIS, Redis, gRPC, Kubernetes
Difficulty Medium
Monetization Revenue‑ready: pay‑per‑query + tiered subscription

Notes

  • Addresses frustration: “If joins are a critical performance‑sensitive operation, the most important property of a DGGS is congruency.”
  • Users currently rely on “R‑trees” or “elastic search” hacks; JoinMate offers a clean, analytic‑centric alternative.
  • Discussion potential: comparing bandwidth savings vs. traditional spatial indexes.

HexViz: Mixed‑Resolution H3 Visualizer

Summary

  • A web component that renders mixed‑resolution H3 data without gaps by drawing child outlines for coarser cells.
  • Enables accurate, gap‑free visualizations for map developers and data journalists.

Details

Key Value
Target Audience Map developers, data journalists, UI/UX designers
Core Feature Automatic child‑outline rendering, interactive zoom, resolution selector
Tech Stack TypeScript, React, Mapbox GL, D3
Difficulty Low
Monetization Hobby

Notes

  • Solves the “weird overlaps and gaps” issue raised by ajfriend: “plot the coarser cells not with their native geometry, but using the outline of their children.”
  • Provides a practical utility for visualizing H3 data at any resolution without manual workarounds.
  • Discussion hook: extending to other DGGS or integrating with HexViz for analytics dashboards.

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