fsst array: AllTrue and AllFalse are handled by filter fn

encodings/fsst/src/kernel.rs

@@ -9,6 +9,7 @@ use vortex_array::arrays::FilterArray;
 use vortex_array::arrays::FilterVTable;
 use vortex_array::arrays::VarBinVTable;
 use vortex_array::compute::FilterKernel;
+use vortex_array::compute::filter_preconditions;
 use vortex_array::kernel::ExecuteParentKernel;
 use vortex_array::kernel::ParentKernelSet;
 use vortex_array::matchers::Exact;
@@ -37,6 +38,11 @@ impl ExecuteParentKernel<FSSTVTable> for FSSTFilterKernel {
         _child_idx: usize,
         _ctx: &mut ExecutionCtx,
     ) -> VortexResult<Option<ArrayRef>> {
+        // TODO(joe): add a pattern to adding checks to all filter impls
+        let mask = parent.filter_mask();
+        if let Some(array) = filter_preconditions(array.as_ref(), mask) {
+            return Ok(Some(array));
+        }
         // TODO(ngates): pass execution context when we update the FilterKernel trait.
         let filtered_codes =
             FilterKernel::filter(&VarBinVTable, array.codes(), parent.filter_mask())?
@@ -214,4 +220,19 @@ mod tests {
         assert_arrays_eq!(result.into_array(), expected);
         Ok(())
     }
+
+    #[test]
+    fn test_fsst_filter_all_true() -> VortexResult<()> {
+        let fsst_array = build_test_fsst_array();
+        assert_eq!(fsst_array.len(), 10);
+
+        let mask = Mask::new_true(10);
+
+        let filter_array = fsst_array.filter(mask)?;
+        let mut ctx = SESSION.create_execution_ctx();
+        let result = filter_array.execute::<Canonical>(&mut ctx)?.into_array();
+
+        assert_arrays_eq!(result, fsst_array);
+        Ok(())
+    }
 }

vortex-array/src/compute/filter.rs

@@ -79,6 +79,22 @@ pub fn filter(array: &dyn Array, mask: &Mask) -> VortexResult<ArrayRef> {
     Ok(array.filter(mask.clone())?.to_canonical()?.into_array())
 }
 
+///  The set of common preconditions that apply to all arrays.
+pub fn filter_preconditions(array: &dyn Array, mask: &Mask) -> Option<ArrayRef> {
+    let true_count = mask.true_count();
+    // Fast-path for empty mask.
+    if true_count == 0 {
+        return Some(Canonical::empty(array.dtype()).into_array());
+    }
+
+    // Fast-path for full mask
+    if true_count == mask.len() {
+        return Some(array.to_array());
+    }
+
+    None
+}
+
 struct Filter;
 
 impl ComputeFnVTable for Filter {
@@ -97,14 +113,8 @@ impl ComputeFnVTable for Filter {
 
         let true_count = mask.true_count();
 
-        // Fast-path for empty mask.
-        if true_count == 0 {
-            return Ok(Canonical::empty(array.dtype()).into_array().into());
-        }
-
-        // Fast-path for full mask
-        if true_count == mask.len() {
-            return Ok(array.to_array().into());
+        if let Some(array) = filter_preconditions(array, mask) {
+            return Ok(array.into());
         }
 
         // If the entire array is null, then we only need to adjust the length of the array.