Problemsby GlyphTrouble with Polars streaming
3 posts from 2 people2d activeFading, +0 this week
Posts per day
The posts behind it
Streaming engine doesn't error on mismatched length when the input data has one row
...Reproducible example ### Log output ### Issue description The streaming engine doesn't error when I try to add a column that doesn't have the same length as the existing data. The in-memory engine errors. This discrepancy only occurs when the data has one row (e.g. all three...
Mismatch of output type of `list.slice()` with all nulls between in-memory and 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 In the example above,...
`min_by`/`max_by`/`sort_by` with a scalar `by`: in-memory engine raises, streaming broadcasts
### 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 the `by` of...
Companies and products named
About this problem
Evidence
3 posts from 2 people in 1 place, about 2 a week over 8 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 "streaming". First post Oct 6, 2026, latest Oct 13, 2026. Corroborated: 3 or more posts from 2 or more people or places. Method
Other Polars problems
Polars upgrades break working setups
23 posts from 16 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.
Trouble with Polars column
Top post: "Compare lists in one column to the first n elements of another column in Python Polars lazyframes, where n is", one of 20 posts from 16 people on GitHub issues, Stack Overflow.
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 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 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.
Trouble with Polars group
Top post: "Datetime out-of-range in `group_by_dynamic` streaming engine", one of 4 posts from 3 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