[GitHub] [arrow] Dandandan commented on a change in pull request #8903: ARROW-9771: [Rust] [DataFusion] treat predicates separated by AND separately in predicate pushdown

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

Dandandan commented on a change in pull request #8903:
URL: https://github.com/apache/arrow/pull/8903#discussion_r541886004



##########
File path: rust/datafusion/src/optimizer/filter_push_down.rs
##########
@@ -215,13 +215,38 @@ fn issue_filters(
     push_down(&state, &plan)
 }
 
+/// converts "A AND B AND C" => [A, B, C]
+fn split_members(predicate: &Expr) -> Vec<&Expr> {
+    match predicate {
+        Expr::BinaryExpr {
+            right,
+            op: Operator::And,
+            left,
+        } => {
+            let mut a = split_members(&left);
+            a.extend(split_members(&right));

Review comment:
       I think this could be O(n*n) in complexity as expression trees are often nested like `1+(1+(1+(...` and extend just iterates over the right side.
   Probably requires a pretty big expression to become a problem, but still maybe something to think about?




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