Пример

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

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Кейс

Цель: Identify where Polars LazyFrame plans stop being lazy, which inspection properties emit PerformanceWarning, and how caching and row indexing alter query execution DAGs HOW
Пакеты: polars 1.43.2 polars-runtime-32 1.43.2
Окружение: python
Создан: 2026-08-15T04:33:13Z

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

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