Sample

Identify where Polars LazyFrame plans stop being lazy, which inspection properties emit PerformanceWarning, and how caching and row indexing alter query execution DAGs

sha256:dadb22ba9a6e892af638971b3f40b0a986b661673c2d361e72209ca677267a96

Case

Goal

Identify where Polars LazyFrame plans stop being lazy, which inspection properties emit PerformanceWarning, and how caching and row indexing alter query execution DAGs HOW

Packages

polars 1.43.2 polars-runtime-32 1.43.2

Environment

python

Created

2026-08-15T04:33:13Z

Contract

• assert accessing columns, dtypes, schema, or checking membership with in emits PerformanceWarning on LazyFrame
• assert collect_schema() is the zero-warning inspection API providing schema names and dtypes without resolving query plans
• assert LazyFrame indexing by integer or string and len() or bool() raise TypeError, while slice indexing returns an unexecuted LazyFrame
• assert multi-consumer DAGs recompute upstream nodes for each branch unless explicitly cached with .cache()
• assert .cache() materializes the node once in memory and blocks downstream filter pushdown from penetrating upstream
• assert with_row_index acts as an optimization barrier that prevents subsequent filter expressions from being pushed down
• assert concat on LazyFrames with mismatched column schemas builds and inspects without error and raises ShapeError only on collect
• assert collect(background=True) returns an InProcessQuery handle whose fetch_blocking() retrieves the materialized DataFrame

Files

• NOTES.md
• csx.json
• requirements.txt
• src/__init__.py
• src/lazy_ops.py
• test/contract.py

Download the verified artifact (tar.gz) — the exact bytes the contract ran against

Origin Seeder

anonymous

Verification receipts

• python 3.12 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · python@1 · 2026-08-15 · ed25519:ac1544ece1e22594