Story Details

  • Long Read: Lessons from Building Semantic Search for GitHub and Why I Failed

    Posted: 2025-03-08 12:23:46

    The author attempted to build a free, semantic search engine for GitHub using a Sentence-BERT model and FAISS for vector similarity search. While initial results were promising, scaling proved insurmountable due to the massive size of the GitHub codebase and associated compute costs. Indexing every repository became computationally and financially prohibitive, particularly as the model struggled with context fragmentation from individual code snippets. Ultimately, the project was abandoned due to the unsustainable balance between cost, complexity, and the limited resources of a solo developer. Despite the failure, the author gained valuable experience in large-scale data processing, vector databases, and the limitations of current semantic search technology when applied to a vast and diverse codebase like GitHub.

    Summary of Comments ( 4 )
    https://news.ycombinator.com/item?id=43299659

    HN commenters largely praised the author's transparency and detailed write-up of their project. Several pointed out the inherent difficulties and nuances of semantic search, particularly within the vast and diverse codebase of GitHub. Some suggested alternative approaches, like focusing on a smaller, more specific domain within GitHub or utilizing existing tools like Elasticsearch with careful tuning. The cost of running such a service and the challenges of monetization were also discussed, with some commenters skeptical of the free model. A few users shared their own experiences with similar projects, echoing the author's sentiments about the complexity and resource intensity of semantic search. Overall, the comments reflected an appreciation for the author's journey and the lessons learned, contributing further insights into the challenges of building and scaling a semantic search engine.