From c6c2ae622f353386835e50c5ead5bc51bb4e2271 Mon Sep 17 00:00:00 2001
From: Ritchie Vink <ritchie46@gmail.com>
Date: Sun, 21 Jan 2024 10:44:16 +0100
Subject: [PATCH] perf: improve binview filter (#13878)

---
 .../src/array/growable/binview.rs             | 22 +++++++++++++++++++
 crates/polars-arrow/src/compute/filter.rs     | 12 +++++-----
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/crates/polars-arrow/src/array/growable/binview.rs b/crates/polars-arrow/src/array/growable/binview.rs
index 3f597f809219..3db541e9c593 100644
--- a/crates/polars-arrow/src/array/growable/binview.rs
+++ b/crates/polars-arrow/src/array/growable/binview.rs
@@ -114,6 +114,28 @@ impl<'a, T: ViewType + ?Sized> GrowableBinaryViewArray<'a, T> {
                 }
             }));
     }
+
+    #[inline]
+    pub(crate) unsafe fn extend_unchecked_no_buffers(
+        &mut self,
+        index: usize,
+        start: usize,
+        len: usize,
+    ) {
+        let array = *self.arrays.get_unchecked(index);
+
+        extend_validity(&mut self.validity, array, start, len);
+
+        let range = start..start + len;
+
+        self.views
+            .extend(array.views().get_unchecked(range).iter().map(|view| {
+                let len = (*view as u32) as usize;
+                self.total_bytes_len += len;
+
+                *view
+            }))
+    }
 }
 
 impl<'a, T: ViewType + ?Sized> Growable<'a> for GrowableBinaryViewArray<'a, T> {
diff --git a/crates/polars-arrow/src/compute/filter.rs b/crates/polars-arrow/src/compute/filter.rs
index abe9fc58bbd9..09ab1c4645a2 100644
--- a/crates/polars-arrow/src/compute/filter.rs
+++ b/crates/polars-arrow/src/compute/filter.rs
@@ -274,14 +274,14 @@ pub fn filter(array: &dyn Array, filter: &BooleanArray) -> PolarsResult<Box<dyn
         }),
         BinaryView => {
             let iter = SlicesIterator::new(filter.values());
-            let mut mutable = growable::GrowableBinaryViewArray::new(
-                vec![array.as_any().downcast_ref::<BinaryViewArray>().unwrap()],
-                false,
-                iter.slots(),
-            );
+            let array = array.as_any().downcast_ref::<BinaryViewArray>().unwrap();
+            let mut mutable =
+                growable::GrowableBinaryViewArray::new(vec![array], false, iter.slots());
             unsafe {
-                iter.for_each(|(start, len)| mutable.extend_unchecked(0, start, len));
+                // We don't have to correct buffers as there is only one array.
+                iter.for_each(|(start, len)| mutable.extend_unchecked_no_buffers(0, start, len));
             }
+
             Ok(mutable.as_box())
         },
         // Should go via BinaryView