# Polars 1.39.0 — Python Polars 1.39.0

- Product: Polars (https://whatsnew.fyi/product/polars)
- Vendor: Polars
- Date: 2026-03-12
- Version: 1.39.0
- Original notes: https://github.com/pola-rs/polars/releases/tag/py-1.39.0
- Permalink: https://whatsnew.fyi/product/polars/releases/1.39.0

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

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- **changed** — Lower arg_{min,max} to streaming engine
- **changed** — Additional IR slice pushdown after filter pushdown
- **changed** — Streaming first/last on Enum through physical
- **changed** — Fast filter for scalar predicates
- **changed** — Allow SimpleProjection in streaming engine to rename
- **changed** — Streaming cloud download for scan_csv
- **changed** — Drop columns only needed for predicates after the predicate is applied
- **changed** — Run projection pushdown after predicate pushdown
- **changed** — Comparison literal downcasting
- **changed** — Add dynamic predicates for TopK
- **changed** — Increase minimum default parquet row group prefetch to 8
- **changed** — Partial predicate conversion to PyArrow
- **changed** — Streaming cloud download for scan_ndjson and scan_lines
- **changed** — Improve CSV and NDJSON cloud sink performance
- **changed** — Tune cloud writer performance
- **changed** — Allow parallel InMemorySinks in streaming engine
- **added** — Support Expr for holidays in business day calculations
- **added** — Parameter for pivot to always include value column name
- **added** — Extend Expr.reinterpret to all numeric types of the same size
- **added** — Add missing_columns parameter to scan_csv

##### 🚀 Performance improvements

- Lower `arg_{min,max}` to streaming engine (#26845)
- Additional IR slice pushdown after filter pushdown (#26815)
- Streaming first/last on Enum through physical (#26783)
- Fast filter for scalar predicates (#26745)
- Allow SimpleProjection in streaming engine to rename (#26709)
- Streaming cloud download for `scan_csv` (#26637)
- Drop columns only needed for predicates after the predicate is applied (#26703)
- Run projection pushdown after predicate pushdown (#26688)
- Comparison literal downcasting (#26663)
- Add dynamic predicates for TopK (#26495)
- Increase minimum default parquet row group prefetch to 8 (#26632)
- Partial predicate conversion to PyArrow (#26567)
- Streaming cloud download for `scan_ndjson` / `scan_lines` (#26563)
- Grab GIL fewer times during Object join materialization (#26587)
- Improve CSV and NDJSON cloud sink performance (#26545)
- Tune cloud writer performance (#26518)
- Allow parallel InMemorySinks in streaming engine (#26501)
- Add streaming `AsOf` join node (#26398)
- Don't always rechunk on gather of nested types (#26478)

##### ✨ Enhancements

- Support Expr for holidays in business day calculations (#26193)
- Parameter for pivot to always include value column name (#26730)
- Raise error in `.collect_schema()` when `arr.get()` is out-of-bounds (#26866)
- Extend `Expr.reinterpret` to all numeric types of the same size (#26401)
- Add missing\_columns parameter to scan\_csv (#26787)
- Clear no-op scan projections (#26858)
- Support nested datatypes for `{min,max}_by` (#26849)
- Support SQL `ARRAY` init from typed literals (#26622)
- Accept table identifier string in `scan_iceberg()` (#26826)
- Add a convenience `make fresh` command to the Makefile (#26809)
- Expose "use\_zip64" Workbook option for `write_excel` (#26699)
- Add unstable `LazyFrame.sink_iceberg` (#26799)
- Add maintain order argument on implode (#26782)
- Speed up casting primitive to bool by at least 2x (#26823)
- Support ASCII format table input to `pl.from_repr` (#26806)
- Enable rowgroup skipping for float columns (#26805)
- Add expression context to errors (#26716)
- Add Decimal support for product reduction (#26725)
- Support all Iceberg V2 arrow types in sink\_parquet arrow\_schema parameter (#26669)
- Re-work behavior of arrow\_schema parameter on sink\_parquet (#26621)
- Add `contains_dtype()` method for `Schema` (#26661)
- Implement `truncate` as a "to\_zero" rounding mode (#26677)
- More generic streaming GroupBy lowering (#26696)
- Create an `Alignment` TypeAlias (#26668)
- Add basic MemoryManager to track buffered dataframes for out-of-core support later (#26443)
- Add `truncate` Expression for numeric values (#26666)
- Better error messages for hex literal conversion issues in the SQL interface (#26657)
- Add SQL support for `LPAD` and `RPAD` string functions (#26631)
- Support SQL "FROM-first" `SELECT` query syntax (#26598)
- Improve `base_type` typing (#26602)
- Bump Chrono to 0.4.24, enabling stricter parsing of `%.3f`/`%.6f`/`%.9f` specifiers (#26075)
- Expose unstable `assert_schema_equal` in py-polars (#24869)
- Allow parsing of compact ISO 8601 strings (#24629)
- Add optional "label" param to DataFrame `corr` (#26588)
- Streaming cloud download for `scan_ndjson` / `scan_lines` (#26563)
- Configuration to cast integers to floats in `cast_options` for `scan_parquet` (#26492)
- Add escaping to quotes and newlines when reading JSON object into string (#26578)
- Standardise on RFC-5545 when doing datetime arithmetic on timezone-aware datetimes (#26425)
- Support `sas_token` in Azure credential provider (#26565)
- Relax SQL requirement for derived tables and subqueries to have aliases (#26543)
- Add polars-config and pl.Config.reload\_env\_vars() (#26524)
- Record path for object store error raised from sinks (#26541)
- Use CRC64NVME for checksum in aws sinks (#26522)
- Add `get()` for binary Series (#26514)
- Add streaming `AsOf` join node (#26398)
- Add primitive filter -> agg low

_[Truncated at 4000 characters — full notes: https://github.com/pola-rs/polars/releases/tag/py-1.39.0]_