IN LIST: unify bitmap filter implementations#23035
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This was referenced Jun 19, 2026
Replaces HashSet<u8> with a 32-byte stack-allocated bitmap. Provides O(1) membership testing via bit-shifting, significantly reducing memory overhead and improving cache locality. Triggers for UInt8 arrays.
Implements an 8 KB heap-allocated bitmap for UInt16. Maintains O(1) performance while handling the larger value space. Triggers for UInt16 arrays.
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Which issue does this PR close?
INperformance with specialized implementations #19390.Rationale for this change
#23011 and #23012 intentionally introduce the
UInt8andUInt16bitmap filters as concrete implementations. With both widths visible, the shared shape is now clear: each filter builds a fixed-size bitmap from non-nullINlist values and probes it with the input value's integer bit pattern.This PR factors that duplicated bitmap machinery behind a small shared configuration trait. It does not add a new lookup strategy or change which data types use bitmap filters. The next PR uses this shared shape to let same-width signed integers reuse the unsigned bitmap storage.
What changes are included in this PR?
BitmapStoragefor fixed-size bitmap backing stores.BitmapFilterConfigto describe the Arrow type, native value, storage, and index conversion for each bitmap domain.UInt8BitmapFilterandUInt16BitmapFilterimplementations withBitmapFilter<C>.UInt8BitmapConfigandUInt16BitmapConfig.UInt8andUInt16routing behavior unchanged.Are these changes tested?
Yes.
cargo fmt --allcargo test -p datafusion-physical-expr bitmap_filter_ --libcargo test -p datafusion-physical-expr in_list_int_types --libcargo test -p datafusion-physical-expr test_in_list_from_array_type_combinations --libcargo test -p datafusion-physical-expr test_in_list_dictionary_types --libcargo clippy -p datafusion-physical-expr --all-targets --all-features -- -D warningsAre there any user-facing changes?
No. This is an internal refactor only.
Benchmark note
No local benchmark numbers are included for this PR because it is intended to be a behavior-preserving refactor of the bitmap filter implementation. Benchmarks were not rerun for this stack split.