[GitHub] [arrow-datafusion] wiedld commented on a diff in pull request #7379: feat(7181): cascading loser tree merges

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

wiedld commented on code in PR #7379:
URL: https://github.com/apache/arrow-datafusion/pull/7379#discussion_r1302264850


##########
datafusion/core/src/physical_plan/sorts/cursor.rs:
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@@ -99,6 +100,16 @@ pub trait Cursor: Ord {
 
     /// Advance the cursor, returning the previous row index
     fn advance(&mut self) -> usize;
+
+    /// Go to reference row, returning the previous row index
+    fn seek(&mut self, row: usize) -> usize;

Review Comment:
   Seek was added in anticipation of the TODO/planned optimizations.
   
   a.k.a. cycles of slicing and concating of normalized key rows, also matching the cascaded sort recommendations in Graefe 2006.



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