Observed Signal · Jun 8, 2026 · Technical Release · Source: DEV Community · Impact: 1/5 · Sentiment: Positive

Developer Builds Tiny Columnar Format in Pure Python

Executive Signal Summary

A developer published Columna, a teaching-grade columnar storage engine and file format implemented in pure Python (no pandas/pyarrow/numpy). Columna is ~3,000 lines with 81 tests and provides footer-last layout, row groups, per-chunk min/max stats for predicate pushdown, and five encodings (PLAIN, DICTIONARY, RLE, DELTA, BITPACK). The writer encodes columns with all applicable encodings, picks the smallest result, and optionally DEFLATE-compresses pages. On a 50,000-row orders dataset Columna produced a 225 KB file (91% smaller than CSV) and read 98% fewer bytes for a filtered query. Source code and a live file inspector are available on GitHub and a demo site.

Polaris7 AgentPolaris7 Strategic Assessment
High Confidence

Open-source, educational technical project with limited direct impact on the wider AdTech/MarTech industry; useful as a learning resource for data engineers but not an industry-shifting release.

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Key Takeaways & Evidence Grounding

  • Columna is a columnar storage engine and file format implemented in pure Python (no pandas, pyarrow, or numpy).
  • The codebase is about 3,000 lines long and includes 81 tests.
  • Columna uses a footer-last layout with row groups, per-column chunks, pages with headers and CRC32 checksums, and a zlib-compressed JSON footer containing schema, offsets, encodings, and min/max statistics.
  • It implements five encodings: PLAIN, DICTIONARY, RLE, DELTA, and BITPACK, and the writer encodes with all applicable encodings and keeps the smallest result.
  • Benchmark on a 50,000-row orders dataset: file size 225 KB (91% smaller than CSV); reading one of seven columns read 154 KB (94% less); filtered query read 47 KB (98% less).
Primary Source Grounding & Direct Attribution
Direct Origin Attribution
Primary Reporting: DEV Community•Published: Jun 8, 2026
Original Coverage Title: “I Built a Columnar File Format in Pure Python — a tiny, readable Parquet”

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