ursus: A Dataframe Library for Go, and What It Is Honestly Worth

Sun, 20 Sep 2026 19:45:00 +0200

I have spent the last weeks building ursus — a dataframe library for Go modelled on Polars. Lazy execution with a query optimizer, Arrow memory layout, SIMD kernels, and streaming execution that spills to disk instead of falling over.

df, err := ursus.ScanParquet("events.parquet").
 Filter(ursus.Col("price").Gt(5)).
 GroupBy(ursus.Col("region")).
 Agg(
 ursus.Col("price").Sum().Alias("revenue"),
 ursus.Col("qty").Mean().Alias("avg_qty"),
 ).
 Sort(ursus.Desc(ursus.Col("revenue"))).
 Collect(ctx)

The projection reaches the Parquet reader, the filter becomes a row-group predicate, and the group-by runs on every core. None of that shows up in the query.

Arrow on Asadbek Kurbonov

ursus: A Dataframe Library for Go, and What It Is Honestly Worth