How does Parquet handle compression and encoding?

Parquet uses two complementary techniques to minimise storage:

Encoding — applied first, at the column level, to exploit data patterns:

• Dictionary Encoding — replaces repeated values with integer codes. Ideal for low-cardinality columns (e.g., status, country).
• Run-Length Encoding (RLE) — collapses consecutive identical values into (value, count) pairs.
• Delta Encoding — stores differences between successive integers; great for timestamps and monotonic IDs.
• Bit-packing — packs small integers into fewer bits.

Compression codec — applied after encoding to the byte stream:

• Snappy (default in Spark) — fast, moderate ratio (~2–3×).
• GZIP/Zlib — higher ratio (~4–6×) but slower CPU.
• ZSTD — best balance; recommended for most new deployments.
• LZO, LZ4, Brotli — specialised use cases.

Encoding and codec are configured independently per column, so hot columns can use fast codecs while archive columns use ZSTD for maximum compression.

Invest now in Acorns!!! 🚀
Join Acorns and get your $5 bonus!

Acorns is a micro-investing app that automatically invests your "spare change" from daily purchases into diversified, expert-built portfolios of ETFs. It is designed for beginners, allowing you to start investing with as little as $5. The service automates saving and investing. Disclosure: I may receive a referral bonus.

Invest now!!! Get Free equity stock (US, UK only)!

Use Robinhood app to invest in stocks. It is safe and secure. Use the Referral link to claim your free stock when you sign up!.

The Robinhood app makes it easy to trade stocks, crypto and more.

Webull! Receive free stock by signing up using the link: Webull signup.