EmilyMatt commented on code in PR #23619:
URL: https://github.com/apache/datafusion/pull/23619#discussion_r3594130181
##########
datafusion/physical-plan/src/sorts/cursor.rs:
##########
@@ -113,15 +123,23 @@ impl<T: CursorValues> Cursor<T> {
t
}
- pub fn is_eq_to_prev_one(&self, prev_cursor: Option<&Cursor<T>>) -> bool {
+ pub fn is_eq_to_prev_one(&self, prev_value: Option<&T::SingleRowValue>) ->
bool {
if self.offset > 0 {
self.is_eq_to_prev_row()
- } else if let Some(prev_cursor) = prev_cursor {
- self.is_eq_to_prev_row_in_prev_batch(prev_cursor)
+ } else if let Some(prev_value) = prev_value {
+ T::eq_to_single_row_value(&self.values, self.offset, prev_value)
} else {
false
}
}
+
+ /// Extract an owned copy of the last row in this cursor, decoupled from
+ /// any buffer the cursor's [`CursorValues`] holds. Used to remember a
+ /// partition's last row across a batch boundary without keeping the
+ /// whole exhausted batch's memory alive (see [`Self::is_eq_to_prev_one`]).
+ pub fn last_value(&self) -> T::SingleRowValue {
+ self.values.get_value(self.values.len() - 1)
Review Comment:
can len() ever be 0?
##########
datafusion/physical-plan/src/sorts/cursor.rs:
##########
@@ -113,15 +123,23 @@ impl<T: CursorValues> Cursor<T> {
t
}
- pub fn is_eq_to_prev_one(&self, prev_cursor: Option<&Cursor<T>>) -> bool {
+ pub fn is_eq_to_prev_one(&self, prev_value: Option<&T::SingleRowValue>) ->
bool {
if self.offset > 0 {
self.is_eq_to_prev_row()
- } else if let Some(prev_cursor) = prev_cursor {
- self.is_eq_to_prev_row_in_prev_batch(prev_cursor)
+ } else if let Some(prev_value) = prev_value {
+ T::eq_to_single_row_value(&self.values, self.offset, prev_value)
} else {
false
}
}
+
+ /// Extract an owned copy of the last row in this cursor, decoupled from
+ /// any buffer the cursor's [`CursorValues`] holds. Used to remember a
+ /// partition's last row across a batch boundary without keeping the
+ /// whole exhausted batch's memory alive (see [`Self::is_eq_to_prev_one`]).
+ pub fn last_value(&self) -> T::SingleRowValue {
+ self.values.get_value(self.values.len() - 1)
Review Comment:
I feel like this should be defensive either way
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