[PySpark] feat: add explode and explode_outer to experimental PySpark API#415
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tinovyatkin wants to merge 1 commit intoduckdb:mainfrom
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[PySpark] feat: add explode and explode_outer to experimental PySpark API#415tinovyatkin wants to merge 1 commit intoduckdb:mainfrom
tinovyatkin wants to merge 1 commit intoduckdb:mainfrom
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Implement the `explode` and `explode_outer` collection functions for DuckDB's experimental PySpark-compatible API. These are commonly used PySpark functions for flattening array columns into individual rows. - `explode(col)` maps to DuckDB's `unnest()`, dropping NULL/empty arrays - `explode_outer(col)` preserves NULL/empty array rows by substituting `[NULL]` before unnesting via a CASE expression Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
explode(col)andexplode_outer(col)collection functions in the experimental PySpark-compatible APIexplodemaps to DuckDB'sunnest()function, which natively drops rows with NULL/empty arrays (matching PySpark semantics)explode_outerpreserves rows with NULL/empty arrays by substituting[NULL]via aCaseExpressionbefore unnestingImplementation details
explode(col)is a one-liner wrappingFunctionExpression("unnest", ...), since DuckDB'sunnestalready matches PySpark'sexplodebehavior for arrays (drops NULL/empty).explode_outer(col)builds aCaseExpressionthat replaces NULL or empty arrays with[NULL]before passing tounnest, so those rows appear in the output with a NULL value instead of being dropped.Both functions follow the existing patterns used by other collection functions like
flatten,array_compact, andarray_removeinfunctions.py.Not included (future work)
posexplode/posexplode_outer— these produce multiple output columns (pos + value), which requires multi-column generator support beyond the currentColumnabstractionunnestdoesn't accept MAP types directly; this would requiremap_entries()wrapping and struct field extraction