[GitHub] [arrow-rs] alamb commented on a diff in pull request #4470: Append Row to Rows (#4466)

["alamb (via GitHub)" <gi...@apache.org>]

alamb commented on code in PR #4470:
URL: https://github.com/apache/arrow-rs/pull/4470#discussion_r1247865163


##########
arrow-row/src/lib.rs:
##########
@@ -832,14 +874,25 @@ struct RowConfig {
 #[derive(Debug)]
 pub struct Rows {
     /// Underlying row bytes
-    buffer: Box<[u8]>,
+    buffer: Vec<u8>,
     /// Row `i` has data `&buffer[offsets[i]..offsets[i+1]]`
-    offsets: Box<[usize]>,
+    offsets: Vec<usize>,
     /// The config for these rows
     config: RowConfig,
 }
 
 impl Rows {
+    /// Append a [`Row`] to this [`Rows`]
+    pub fn push(&mut self, row: Row<'_>) {
+        assert!(
+            Arc::ptr_eq(&row.config.fields, &self.config.fields),
+            "row was not produced by this RowConverter"
+        );
+        self.config.validate_utf8 |= row.config.validate_utf8;

Review Comment:
   Why doesn't this just assert that the values of `validate_utf8` are the same?



##########
arrow-row/src/lib.rs:
##########
@@ -756,6 +756,48 @@ impl RowConverter {
         unsafe { self.convert_raw(&mut rows, validate_utf8) }
     }
 
+    /// Returns an empty [`Rows`] with capacity for `row_capacity` rows with
+    /// a total length of `data_capacity`
+    ///
+    /// This can be used to buffer a selection of [`Row`]
+    ///
+    /// ```
+    /// # use std::sync::Arc;
+    /// # use std::collections::HashSet;
+    /// # use arrow_array::cast::AsArray;
+    /// # use arrow_array::StringArray;
+    /// # use arrow_row::{Row, RowConverter, SortField};
+    /// # use arrow_schema::DataType;
+    /// #
+    /// let mut converter = RowConverter::new(vec![SortField::new(DataType::Utf8)]).unwrap();

Review Comment:
   ```suggestion
       /// // This example shows how to buffer only the Row values
       /// let mut converter = RowConverter::new(vec![SortField::new(DataType::Utf8)]).unwrap();
   ```



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