Apache Parquet File Anatomy: Row Groups, Column...

If you use Spark, Athena, Iceberg, Snowflake, DuckDB, or Pandas, you’ve probably worked with Parquet hundreds of times. But most of us first learn Parquet as a simple rule of thumb: it’s columnar, compressed, and great for analytics. That’s true, but it leaves out the most interesting part — why Parquet performs so well in the first place. Under the hood, a Parquet file is not just a blob of compressed data. It has a deliberate internal structure made of row groups, column chunks, pages, and foo