fix: collect_columns quadratic complexity

Fix accidental $O(n^2)$ in `collect_columns`.

There are the following ways to insert a clone into a hash set:

- **clone before check:** Basically `set.insert(x.clone())`. That's
  rather expensive if you have a lot of duplicates.
- **iter & clone:** That's what we do right now, but that's in $O(n^2)$.
- **check & insert:** Basically `if !set.contains(x) {set.insert(x.clone())}`
  That requires two hash probes though.
- **entry-based API:** Sadly the stdlib doesn't really offer any
  handle/entry-based APIs yet (see rust-lang/rust#60896 ),
  but `hashbrown` does, so we can use the nice
  `set.get_or_insert_owned(x)` which will only clone the reference if it
  doesn't exists yet and only hashes once.

We now use the last approach.

Author: crepererum

datafusion/physical-expr/src/utils/mod.rs

@@ -17,9 +17,10 @@
 
 mod guarantee;
 pub use guarantee::{Guarantee, LiteralGuarantee};
+use hashbrown::HashSet;
 
 use std::borrow::Borrow;
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 use std::sync::Arc;
 
 use crate::expressions::{BinaryExpr, Column};
@@ -204,9 +205,7 @@ pub fn collect_columns(expr: &Arc<dyn PhysicalExpr>) -> HashSet<Column> {
     let mut columns = HashSet::<Column>::new();
     expr.apply(|expr| {
         if let Some(column) = expr.as_any().downcast_ref::<Column>() {
-            if !columns.iter().any(|c| c.eq(column)) {
-                columns.insert(column.clone());
-            }
+            columns.get_or_insert_owned(column);
         }
         Ok(TreeNodeRecursion::Continue)
     })