Reuse fixed-width storage for decimal arrays

Signed-off-by: Connor Tsui <connor.tsui20@gmail.com>

Author: connortsui20

vortex-array/src/arrays/decimal/array.rs

@@ -28,6 +28,8 @@ use crate::array::validity_to_child;
 use crate::arrays::Decimal;
 use crate::arrays::DecimalArray;
 use crate::arrays::PrimitiveArray;
+use crate::arrays::fixed_width::FixedWidth;
+use crate::arrays::fixed_width::FixedWidthData;
 use crate::arrays::primitive::PrimitiveArrayExt;
 use crate::buffer::BufferHandle;
 use crate::dtype::BigCast;
@@ -107,7 +109,7 @@ pub(super) const SLOT_NAMES: [&str; NUM_SLOTS] = ["validity"];
 #[derive(Clone, Debug)]
 pub struct DecimalData {
     pub(super) decimal_dtype: DecimalDType,
-    pub(super) values: BufferHandle,
+    pub(super) values: FixedWidthData,
     pub(super) values_type: DecimalType,
 }
 
@@ -121,6 +123,16 @@ impl Display for DecimalData {
     }
 }
 
+impl FixedWidth for DecimalData {
+    fn fixed_width(&self) -> &FixedWidthData {
+        &self.values
+    }
+
+    fn fixed_width_mut(&mut self) -> &mut FixedWidthData {
+        &mut self.values
+    }
+}
+
 pub struct DecimalDataParts {
     pub decimal_dtype: DecimalDType,
     pub values: BufferHandle,
@@ -287,7 +299,7 @@ impl DecimalData {
     ) -> Self {
         Self {
             decimal_dtype,
-            values,
+            values: FixedWidthData::new(values),
             values_type,
         }
     }
@@ -391,7 +403,7 @@ impl Array<Decimal> {
         let data = self.into_data();
         DecimalDataParts {
             decimal_dtype,
-            values: data.values,
+            values: data.values.into_buffer_handle(),
             values_type: data.values_type,
             validity,
         }

vortex-array/src/arrays/decimal/vtable/mod.rs

@@ -8,7 +8,6 @@ use vortex_buffer::Alignment;
 use vortex_error::VortexResult;
 use vortex_error::vortex_bail;
 use vortex_error::vortex_ensure;
-use vortex_error::vortex_panic;
 use vortex_session::VortexSession;
 
 use crate::ArrayParts;
@@ -19,6 +18,7 @@ use crate::array::Array;
 use crate::array::ArrayView;
 use crate::array::VTable;
 use crate::arrays::decimal::DecimalData;
+use crate::arrays::fixed_width;
 use crate::buffer::BufferHandle;
 use crate::builders::ArrayBuilder;
 use crate::builders::DecimalBuilder;
@@ -80,40 +80,24 @@ impl VTable for Decimal {
         *ID
     }
 
-    fn nbuffers(_array: ArrayView<'_, Self>) -> usize {
-        1
+    fn nbuffers(array: ArrayView<'_, Self>) -> usize {
+        fixed_width::nbuffers(array)
     }
 
     fn buffer(array: ArrayView<'_, Self>, idx: usize) -> BufferHandle {
-        match idx {
-            0 => array.values.clone(),
-            _ => vortex_panic!("DecimalArray buffer index {idx} out of bounds"),
-        }
+        fixed_width::buffer(array, idx)
     }
 
-    fn buffer_name(_array: ArrayView<'_, Self>, idx: usize) -> Option<String> {
-        match idx {
-            0 => Some("values".to_string()),
-            _ => None,
-        }
+    fn buffer_name(array: ArrayView<'_, Self>, idx: usize) -> Option<String> {
+        fixed_width::buffer_name(array, idx)
     }
 
     fn with_buffers(
         &self,
         array: ArrayView<'_, Self>,
         buffers: &[BufferHandle],
     ) -> VortexResult<ArrayParts<Self>> {
-        vortex_ensure!(
-            buffers.len() == 1,
-            "Expected 1 buffer, got {}",
-            buffers.len()
-        );
-        let mut data = array.data().clone();
-        data.values = buffers[0].clone();
-        Ok(
-            ArrayParts::new(self.clone(), array.dtype().clone(), array.len(), data)
-                .with_slots(array.slots().iter().cloned().collect()),
-        )
+        fixed_width::with_buffers(self, array, buffers)
     }
 
     fn serialize(