~/talk

Using Row Groups for fast filtering of large parquet files

Talkat PyData Tel Aviv 2024 · 2024-09-25..09-26· [databases, web-performance]
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Shows that tuning Parquet row groups and layout cuts IO and cloud cost: reading footer metadata with pyarrow’s ParquetFile and adding per‑group stats (min/max, sums, custom version tags) lets engines push down filters via DuckDB query plan checks. On a 3 GB dataset (18M rows) splitting into 500,000‑row row groups moves a full‑scan case from ~34s to roughly 40–50× speedup; sorting by key further yields ~50× gains and far fewer s3fs read calls.

AI-written summary · about

  1. 0:00Introduction to Parquet
  2. 10:22Understanding row groups
  3. 17:37Benchmarking row groups
  4. 21:31Optimizing data organization
  5. 24:49Choosing row group size
  6. 27:03Cost savings with row groups
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