Compression: Bytes Versus CPU

Concepts covered: paCompression, paSplittability, paZstdSnappy

Compression is the lever that trades CPU cycles for bytes. Smaller files mean fewer bytes read from disk or network, which usually wins. Smaller files also mean more CPU spent decompressing on read and compressing on write. The tradeoff is rarely close in modern analytical workloads: I/O is slow and getting slower relative to CPU, so the bytes saved are almost always worth the cycles spent. The interesting choice is which codec, not whether to compress. The Codecs in Use ZSTD has become the modern default in many stacks because it offers GZIP-like ratios at near-Snappy speeds. Spark, Iceberg, Delta, and Trino all support ZSTD natively. Snappy remains the historical default for Parquet because it was the original choice when Parquet emerged at Twitter and Cloudera around 2013, and changing

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