Problemsby GlyphBad data slips through Polars unnoticed
3 posts from 3 people3d activeFading, +0 this week
Posts per day
The posts behind it
Partitioned write puts a NULL key and the string "__HIVE_DEFAULT_PARTITION__" into the same file: rows silently lost, file sometimes unreadable
### 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 Output (main): The streaming sink behaves the same:...
Python data contract with Polars dataframe in mind?
...but not sure if it is worth it to add it to our dependencies just for this sole reason. Any tips?. (P.s. we will use YAML files and Kedro to orchestrate workflows.).
Feature request: Add Wilder's Smoothing / Moving Average (rma)
...conceptually become: and ATR: This would also avoid relying on implementation-specific workarounds involving `shift`, `fill_null`, or Python-side loops for a fundamentally standard rolling/smoothing operation. ## Expected benefit A first-class Wilder smoothing operation would...
Companies and products named
About this problem
Evidence
3 posts from 3 people in 2 places, about 1 a week over 45 days. Mostly on pola-rs/polars, r/dataengineering. Tools named alongside: PyPI.
Frustration Frustration 0 of 3· Seen on GitHub issues, Reddit
How it was grouped
Posts that state a pain and match the "data-quality" rule about Polars. First post Sep 4, 2026, latest Oct 18, 2026. Corroborated: 3 or more posts from 2 or more people or places. Method
The same problem elsewhere
Bad data slips into production unnoticed
21 posts from 21 people on GitHub issues, Reddit, Stack Overflow.
Bad data slips through Databricks unnoticed
3 posts from 3 people on Reddit.
Bad data slips through Snowflake unnoticed
3 posts from 3 people on Reddit, Hacker News.
Bad data slips through Apache Iceberg unnoticed
3 posts from 3 people on GitHub issues.
Bad data slips through Apache Spark unnoticed
2 posts from 2 people on GitHub issues. Unverified.
Bad data slips through PostgreSQL unnoticed
2 posts from 2 people on Stack Overflow. Unverified.
Bad data slips through Claude unnoticed
2 posts from 1 person on Reddit. Unverified.
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.
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.
Trouble with Polars value
Top post: "polars.read_excel() value error on very large date", one of 3 posts from 3 people on GitHub issues.
History