Blog

Building a Parquet-backed data API, end to end

June 19, 2026

An HTTP API over a single Parquet file: polars scan_parquet per request, tests that never touch the real data, and a Railway deploy. Plus a follow-up to my last post, where the page cache that makes local reads fast turns out to be billed as memory.

Why Reading Parquet from S3 Is Slow (Even In-Network) and What I Did Instead

April 01, 2026

S3 in-network reads still have a ~300ms latency floor. Downloading parquet files to ephemeral disk at startup gave me local-disk speeds (~3ms) for free on Railway.