From 330c8ee763c5364b92eae0123709c6fddb26f1b6 Mon Sep 17 00:00:00 2001
From: Liang-Chi Hsieh <viirya@gmail.com>
Date: Wed, 13 Jul 2022 18:31:27 -0700
Subject: [PATCH 1/2] Optimize filter_dict

---
 arrow/src/array/array_dictionary.rs | 22 ++++++++++++++++++++++
 arrow/src/compute/kernels/filter.rs |  8 +++++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/arrow/src/array/array_dictionary.rs b/arrow/src/array/array_dictionary.rs
index 8a7e05aac33..1a6ae66a646 100644
--- a/arrow/src/array/array_dictionary.rs
+++ b/arrow/src/array/array_dictionary.rs
@@ -151,6 +151,28 @@ impl<K: ArrowPrimitiveType> DictionaryArray<K> {
         Ok(array.into())
     }
 
+    /// Create a new DictionaryArray directly from specified keys
+    /// (indexes into the dictionary) and values (dictionary)
+    /// array, and the corresponding ArrayData. This is used internally
+    /// for the usage like filter kernel.
+    ///
+    /// # Safety
+    ///
+    /// The input keys, values and data must form a valid DictionaryArray,
+    /// or undefined behavior can results.
+    pub(crate) unsafe fn try_new_unchecked(
+        keys: PrimitiveArray<K>,
+        values: ArrayRef,
+        data: ArrayData,
+    ) -> Self {
+        Self {
+            data,
+            keys,
+            values,
+            is_ordered: false,
+        }
+    }
+
     /// Return an array view of the keys of this dictionary as a PrimitiveArray.
     pub fn keys(&self) -> &PrimitiveArray<K> {
         &self.keys
diff --git a/arrow/src/compute/kernels/filter.rs b/arrow/src/compute/kernels/filter.rs
index 1af93bff5ad..7b88de7b8e8 100644
--- a/arrow/src/compute/kernels/filter.rs
+++ b/arrow/src/compute/kernels/filter.rs
@@ -786,7 +786,13 @@ where
         )
     };
 
-    DictionaryArray::<T>::from(data)
+    unsafe {
+        DictionaryArray::<T>::try_new_unchecked(
+            filtered_keys,
+            array.values().clone(),
+            data,
+        )
+    }
 }
 
 #[cfg(test)]

From 3983af9a48d610af39cdcfb34d351050488ef897 Mon Sep 17 00:00:00 2001
From: Liang-Chi Hsieh <viirya@gmail.com>
Date: Wed, 13 Jul 2022 20:34:03 -0700
Subject: [PATCH 2/2] For review

---
 arrow/src/array/array_dictionary.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arrow/src/array/array_dictionary.rs b/arrow/src/array/array_dictionary.rs
index 1a6ae66a646..9350daae53e 100644
--- a/arrow/src/array/array_dictionary.rs
+++ b/arrow/src/array/array_dictionary.rs
@@ -159,7 +159,7 @@ impl<K: ArrowPrimitiveType> DictionaryArray<K> {
     /// # Safety
     ///
     /// The input keys, values and data must form a valid DictionaryArray,
-    /// or undefined behavior can results.
+    /// or undefined behavior can occur.
     pub(crate) unsafe fn try_new_unchecked(
         keys: PrimitiveArray<K>,
         values: ArrayRef,