IcefallDB: Time Travel on Plain Parquet Files

Tue, 14 Jul 2026 10:04:25 -0500

Parquet is the columnar format that ate the data lake, and for good reason: it compresses well, it reads fast, every analytics engine from DuckDB to Spark to DataFusion speaks it natively, and the files are just sitting there on disk waiting to be queried by anything that can open them, which is the same property that made SQLite appealing for a different class of problem. The catch, and it is a significant catch, is that Parquet is immutable by design, the format spec has no concept of updating a row in place, deleting a tuple, or merging two versions of a record, and the moment you need any of those operations you are in the business of rewriting files or building a layer on top that pretends mutability exists; IcefallDB is that layer, and the interesting work was making the pretension convincing enough that you stop noticing it.

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IcefallDB: Time Travel on Plain Parquet Files