Problemsby GlyphTrouble with Polars column
20 posts from 16 people16d activeFading, +1 this week
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polars add_missing_columns raises AttributeError for a column with a default and no dtype
**Describe the bug** With `pandera.polars`, `add_missing_columns=True` and a missing column defined as `Column(default=1)` (no dtype), `validate` raises `AttributeError: 'NoneType' object has no attribute 'type'` instead of adding the column. The pandas backend handles this case...
Compare lists in one column to the first n elements of another column in Python Polars lazyframes, where n is dynamically determined from index
I'm trying to compare words present within sentences in one column, to the first n words in a wordlist (in another column), and return the words in the sentences that don't exist in that subset of the wordlist (to a new column). The "n" amount should be dynamically determined by...
Polars Enum dtypes raise TypeError on `==`/`hash()`, and `Column(pl.Enum)` cannot validate any Enum column
**Describe the bug** `pandera.engines.polars_engine.Enum` stores its categories as a compared dataclass field. `pl.Enum.categories` is a `pl.Series`, which has no truth value and is unhashable, so two Enum dtypes with the same categories cannot be compared or hashed. This breaks...
Should `clip(np.nan)` on an integer column be a no-op instead of erroring?
### 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 If comparing an Int and `NaN`...
Wrong `max`/`n_unique` after a `rolling` `first`/`min` with empty windows on a sorted column
### 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 ### Issue description The empty windows put nulls between the...
GPU engine rejects adding an untyped null column and reordering it in a projection
### 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 Adding...
GPU engine rejects replacing a column with an untyped null literal
### 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 Replacing the String column...
Lazy join returns wrong data when a suffixed column (id_right) has the same name as the right join key
### 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 both tables have an `id`...
SQL: unknown and ambiguous column names are not reported outside SELECT and WHERE
### Checks - [x] I have checked that this issue has not already been reported. - [x] I have confirmed this bug exists on the latest version of Polars. ### Reproducible example ### Issue description Names are checked in SELECT and WHERE, as in `SELECT v FROM a JOIN b ON a.id =...
SQL: `CROSS JOIN UNNEST(col, col)` with the same column twice panics
### Checks - [x] I have checked that this issue has not already been reported. - [x] I have confirmed this bug exists on the latest version of Polars. ### Reproducible example ### Log output ### Issue description A lateral `UNNEST` that names the same column twice panics. With...
`read_csv` ignores file source column in `schema_overrides`
### 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. ### Issue description When the `source` column is included in `schema_overrides`, it is...
pivot: peak memory grows ~1 byte per row per output column (4 GB for a 50 x 2000 pivot of a 180 MB frame)
### Checks - [x] I have checked that this issue has not already been reported. - [x] I have confirmed this bug exists on the latest version of Polars (2.0.0). ### Reproducible example Each mode is run in its own process (`python repro.py pivot`, then `python repro.py...
pandera.polars: Decimal column raises AssertionError instead of failing validation when the column isn't a decimal
**Describe the bug** In `pandera.polars`, a column declared as `pl.Decimal(p, s)` raises `AssertionError` when the frame's column isn't a decimal at all, such as a `String` or `Float64` column. It should fail validation with a `SchemaError`. `validate(df, lazy=True)` raises the...
SQL: struct field in a subquery is read as an outer column, returning wrong rows
### 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 `s.f` is field `f` of the...
SQL: unqualified column in an IN-subquery is resolved against the outer tables and reported ambiguous
### 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 The unqualified `DUID` inside...
Filtering a `Categorical` column with `is_in` on a list of strings sometimes drops rows
### 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 Filtering a `Categorical`...
Parquet metadata pruning is disabled for scans with a column mapping (Iceberg)
[prune_parquet_metadata](https://github.com/pola-rs/polars/blob/main/crates/polars-plan/src/plans/optimizer/parquet_metadata_prune.rs) trims each retained footer down to the projected and predicate columns, shrinking the metadata that Polars Cloud serializes to workers. It...
pl.list fails to broadcast leading scalar input against column
### 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 pl.list behavior depends on...
Panic on empty join result with Array column when input is multi-chunk
### 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 This is closely related to...
`rolling_rank_by` nulls column when last value is null
### 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 last value of a...
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About this problem
Evidence
20 posts from 16 people in 3 places, about 2 a week over 66 days. Mostly on pola-rs/polars, unionai-oss/pandera, Stack Overflow [python-polars]. Tools named alongside: PyPI, GitHub, DuckDB, PostgreSQL.
Frustration Frustration 0 of 3· Seen on GitHub issues, Stack Overflow
Summary, model-written
Polars users experience inconsistent list behaviors, errors with column values, and metadata pruning issues.
How it was grouped
Posts about Polars with no known issue, sharing the word "column". First post Aug 30, 2026, latest Nov 3, 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 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.
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