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pola-rs / polars

Dataframes powered by a multithreaded, vectorized query engine, written in Rust
https://docs.pola.rs
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Rust docs don't note when the `parquet` feature is needed #15291

Open nk9 opened 7 months ago

nk9 commented 7 months ago

Description

The Quickstart provides code which doesn't work out of the box after installing just the polars crate. You have to install the parquet and lazy features as well. However, the Quickstart docs don't mention this.

Also, the scan_parquet function also requies the parquet feature, but this is not indicated either. There are other feature requirements listed on that page, which would lead one to think that all feature requirements were called out, but this is not the case.

I think the feature requirement should be mentioned in both cases.

Link

https://docs.rs/polars/latest/polars/prelude/struct.LazyFrame.html#method.scan_parquet

nk9 commented 4 months ago

The Quickstart does say "We recommend to build your queries directly with polars-lazy." But… what does that mean? Are beginning users supposed to cargo add polars_lazy? What's the difference between that and polars with the lazy feature enabled? Does the sentence mean that users are recommended to call df.lazy().do_stuff()? Maybe both?

For beginners, this wording and link are pretty confusing. They've installed polars and gone to look at how to use it… and now they're being pointed at a different crate.