kosiew commented on code in PR #23299:
URL: https://github.com/apache/datafusion/pull/23299#discussion_r3519762834
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datafusion/physical-expr/src/expressions/in_list/primitive_filter.rs:
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@@ -78,23 +78,57 @@ impl BitmapStorage for Box<[u64; 1024]> {
/// Arrow primitive types supported by [`BitmapFilter`].
///
/// Arrow already defines the Rust value type as `T::Native`. This trait only
-/// supplies the bitmap storage size for the two integer domains that are small
-/// enough to represent with one bit per possible value.
+/// supplies the bitmap storage size and maps values to their bit-pattern index
+/// for the two integer domains that are small enough to represent with one bit
+/// per possible value.
pub(super) trait BitmapFilterType:
ArrowPrimitiveType + Send + Sync + 'static
{
type Storage: BitmapStorage;
+
+ fn index(value: Self::Native) -> usize;
+}
+
+/// `Int8` has 256 possible bit patterns, so four `u64` words cover the full
domain.
+impl BitmapFilterType for Int8Type {
+ type Storage = [u64; 4];
+
+ #[inline(always)]
+ fn index(value: Self::Native) -> usize {
+ value as u8 as usize
+ }
}
/// `UInt8` has 256 possible values, so four `u64` words cover the full domain.
impl BitmapFilterType for UInt8Type {
type Storage = [u64; 4];
+
+ #[inline(always)]
+ fn index(value: Self::Native) -> usize {
+ value as usize
+ }
+}
+
+/// `Int16` has 65,536 possible bit patterns, so 1,024 `u64` words cover the
full
+/// domain.
+impl BitmapFilterType for Int16Type {
+ type Storage = Box<[u64; 1024]>;
+
+ #[inline(always)]
+ fn index(value: Self::Native) -> usize {
+ value as u16 as usize
Review Comment:
I think this is good as an comment within the code
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