alamb commented on code in PR #4736:
URL: https://github.com/apache/arrow-rs/pull/4736#discussion_r1305923015
##########
arrow-row/src/lib.rs:
##########
@@ -1445,6 +1446,70 @@ unsafe fn decode_column(
Ok(array)
}
+macro_rules! downcast_dict {
+ ($array:ident, $key:ident) => {{
+ $array
+ .as_any()
+ .downcast_ref::<DictionaryArray<$key>>()
+ .unwrap()
+ }};
+}
+
+const LOW_CARDINALITY_THRESHOLD: usize = 10;
+
+#[derive(Debug)]
+pub struct CardinalityAwareRowConverter {
+ inner: RowConverter,
+ done: bool,
+}
+
+impl CardinalityAwareRowConverter {
+ pub fn new(fields: Vec<SortField>) -> Result<Self, ArrowError> {
+ Ok(Self {
+ inner: RowConverter::new(fields)?,
+ done: false,
+ })
+ }
+
+ pub fn size(&self) -> usize {
+ self.inner.size()
+ }
+
+ pub fn convert_rows(&self, rows: &Rows) -> Result<Vec<ArrayRef>,
ArrowError> {
+ self.inner.convert_rows(rows)
+ }
+
+ pub fn convert_columns(
+ &mut self,
+ columns: &[ArrayRef]) -> Result<Rows, ArrowError> {
+ if !self.done {
+ for (i, col) in columns.iter().enumerate() {
+ if let DataType::Dictionary(k, _) = col.data_type() {
+ // let cardinality =
col.as_any().downcast_ref::<DictionaryArray<Int32Type>>().unwrap().values().len();
+ let cardinality = match k.as_ref() {
Review Comment:
Makes sense. Thank you
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