Framework
Fast, multi-threaded DataFrame library written in Rust with Python bindings, used for querying and transforming tabular data.
Polars 2.0.0 runs lazy queries on the streaming engine by default, and a left join on that engine no longer keeps row order. A dev.to author's repro shows the change raising no error and leaving every value correct.
Reality
Aida van de Wetering has pushed about 125 commits to GeoPolars' dev branch since mid-September, rebuilding it as a geo expression namespace inside Polars. Polars teams with spatial work now have something to test before they reach for GeoPandas, though the project is still a prototype.
Reality
Polars 2.0 runs LazyFrame.collect() on its streaming engine by default, a dev.to upgrade guide reports. One environment variable pins the old engine, so teams can fix the loud API breaks before hunting row-order changes that raise no error.
Reality
A week of measurements on one Mac mini puts the lru_cache wrapper around strptime at 3x when dates repeat and slightly slower when they do not. A Polars 2.0 release candidate finishes the same report in 0.13 s.
Reality
A cross-sectional reversal baseline on 15-minute Bybit perpetual bars won 67 of 76 out-of-sample windows before costs and none of them after. Charging the trading it requires puts breakeven near 2.5 bps per side.
Reality
The AllRates dataset on Hugging Face holds 14.6 million rows in each publisher's own direction and label, so the collecting is finished while the inversion, rounding and missing-day rules stay in your code.
Reality
The release candidate keeps collect's signature and changes what its default resolves to. Group_by, joins and unpivot can now return rows in a different order, and explain() still prints the plan that was not run.
Perspective Coverage
3 publishersReality
Ritchie Vink is selling 2.0 as a boring upgrade. Mostly it is, but engine="auto" now resolves to streaming by default, so joins and group_bys stop carrying incidental row order, and pipelines that leaned on it will drift quietly.
Reality
A dev.to crash course splits pipeline testing into code correctness and data correctness. The split earns its keep because a renamed column produces nulls rather than a stack trace, so nothing pages anyone.
Reality
Interlace drops templating from its dbt-style models. Its argument: parse the SQL, and the dependency graph you were asked to declare twice is already sitting in the FROM clause.
Reality