Problemsby GlyphTrouble with Polars group
4 posts from 3 people3d activeSteady, +2 this week
Posts per day
The posts behind it
Sliced len() over a concat of string-only scans decodes a row group per input since 2.1.0
### Checks - [x] I have checked that this issue has not already been reported. - [x] I have confirmed this bug exists on the [latest version](https://pypi.org/project/polars/) of Polars. ### Reproducible example ### Log output ### Issue description Since 2.1.0, a bounded length...
GPU engine rejects `.is_null().first()` inside a group aggregation
### Checks - [x] I have checked that this issue has not already been reported. - [x] I have confirmed this bug exists on the [latest version](https://pypi.org/project/polars/) of Polars. ### Reproducible example ### Log output ### Issue description Grouping a one-row Int64...
GPU rejects covariance in a group aggregation with `corr` and `ErrorExpr` diagnostics
### Checks - [x] I have checked that this issue has not already been reported. - [x] I have confirmed this bug exists on the [latest version](https://pypi.org/project/polars/) of Polars. ### Reproducible example ### Log output ### Issue description Grouping a single row by `c0`...
Datetime out-of-range in `group_by_dynamic` streaming engine
### Checks - [x] I have checked that this issue has not already been reported. - [x] I have confirmed this bug exists on the [latest version](https://pypi.org/project/polars/) of Polars. ### Reproducible example ### Log output ### Issue description When dates get clamped, the...
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About this problem
Evidence
4 posts from 3 people in 1 place, about 1 a week over 52 days. Mostly on pola-rs/polars. Tools named alongside: PyPI.
Frustration Frustration 0 of 3· Seen on GitHub issues
How it was grouped
Posts about Polars with no known issue, sharing the word "group". First post Sep 7, 2026, latest Oct 28, 2026. Corroborated: 3 or more posts from 2 or more people or places. Method
Other Polars problems
Trouble with Polars column
Top post: "Lazy join returns wrong data when a suffixed column (id_right) has the same name as the right join key", one of 17 posts from 13 people on GitHub issues.
Trouble with Polars unique
Top post: "Streaming engine: multi-column `.unique()` in `group_by().agg()` much slower than in-memory", one of 7 posts from 4 people on GitHub issues.
Trouble with Polars returns
Top post: "GPU `max_horizontal` returns NaN for a finite value followed by NaN", one of 3 posts from 2 people on GitHub issues.
Polars users keep filing bugs
Top post: "Consider upgrading the brotli crate (CVE-2026-111497)", one of 22 posts from 15 people on GitHub issues.
Polars upgrades break working setups
23 posts from 16 people on GitHub issues.
Trouble with Polars parquet
Top post: "`is_in` with more than 100 values does not skip Parquet row groups between the values", one of 7 posts from 7 people on GitHub issues.
Trouble with Polars join
Top post: "Coalescing full join on Int32-vs-Int64 keys with `unique` incorrect", one of 6 posts from 6 people on GitHub issues.
Trouble with Polars instead
Top post: "Series.to_list() panics on out-of-range datetimes instead of raising an error", one of 6 posts from 6 people on GitHub issues.
Bad data slips through Polars unnoticed
3 posts from 3 people on GitHub issues, Reddit.
Polars runs out of memory
3 posts from 3 people on GitHub issues.
Trouble with Polars read
Top post: "`read_database` raises `ImportError` with SQLAlchemy 2.1 when `greenlet` is not installed", one of 3 posts from 3 people on GitHub issues.
Polars error messages are cryptic
3 posts from 2 people on GitHub issues.
History