[GitHub] [arrow-datafusion] Dandandan commented on a diff in pull request #4411: optimize limit push for join case

[GitBox <gi...@apache.org>]

Dandandan commented on code in PR #4411:
URL: https://github.com/apache/arrow-datafusion/pull/4411#discussion_r1034367238


##########
datafusion/optimizer/src/limit_push_down.rs:
##########
@@ -192,6 +196,18 @@ impl OptimizerRule for LimitPushDown {
             LogicalPlan::Join(join) => {
                 let limit = fetch + skip;
                 let new_join = match join.join_type {
+                    JoinType::Left | JoinType::Right | JoinType::Full
+                        if is_no_join_condition(join) =>
+                    {
+                        // push left and right
+                        push_down_join(join, Some(limit), Some(limit))
+                    }
+                    JoinType::LeftSemi | JoinType::LeftAnti
+                        if is_no_join_condition(join) =>
+                    {
+                        // push left
+                        push_down_join(join, Some(limit), None)
+                    }
                     JoinType::Left => push_down_join(join, Some(limit), None),
                     JoinType::Right => push_down_join(join, None, Some(limit)),

Review Comment:
   I think those are the lesser restrictive versions of push down (only to left/right side)



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