Predicate Pushdown

Predicate pushdown moves filtering closer to the data source or reader. For a file scan, supported predicates can enable metadata-based skipping and row filtering before results reach later operators.

For a requested interval [20 January, 21 January), a group ending before the 20th can be excluded. A group spanning the interval is only a candidate: it might contain dates on either side and no matching row. Missing usable statistics require a conservative decision.

Projection chooses columns; partition pruning excludes files using partition values. They can work with predicate pushdown, but a filter may require reading a column absent from the final output. Functions, types, and reader support affect what can be pushed down.

Inspect the query plan and storage metrics to establish actual savings. Correct filtered output or a count of candidate groups alone does not prove how many bytes the engine read. Preserve the exact filter semantics when moving work between operators.

See Data Formats: Parquet, ORC, Avro, and Arrow for worked examples.

Reference: Official format documentation.