From 0bd58de002d1344d7320b8e8c11c397709366775 Mon Sep 17 00:00:00 2001
From: "Jorge C. Leitao" <jorgecarleitao@gmail.com>
Date: Sun, 30 Oct 2022 21:04:22 +0000
Subject: [PATCH] Optimized slice

---
 src/array/binary/mod.rs            | 3 ++-
 src/array/boolean/mod.rs           | 3 ++-
 src/array/fixed_size_binary/mod.rs | 3 ++-
 src/array/fixed_size_list/mod.rs   | 3 ++-
 src/array/list/mod.rs              | 3 ++-
 src/array/map/mod.rs               | 3 ++-
 src/array/primitive/mod.rs         | 3 ++-
 src/array/struct_/mod.rs           | 3 ++-
 src/array/utf8/mod.rs              | 3 ++-
 9 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/array/binary/mod.rs b/src/array/binary/mod.rs
index c55bee2418d..ba68b5231b4 100644
--- a/src/array/binary/mod.rs
+++ b/src/array/binary/mod.rs
@@ -203,7 +203,8 @@ impl<O: Offset> BinaryArray<O> {
         let validity = self
             .validity
             .clone()
-            .map(|x| x.slice_unchecked(offset, length));
+            .map(|bitmap| bitmap.slice_unchecked(offset, length))
+            .and_then(|bitmap| (bitmap.unset_bits() > 0).then(|| bitmap));
         let offsets = self.offsets.clone().slice_unchecked(offset, length + 1);
         Self {
             data_type: self.data_type.clone(),
diff --git a/src/array/boolean/mod.rs b/src/array/boolean/mod.rs
index 2c33ef155ab..d5fe08fbc04 100644
--- a/src/array/boolean/mod.rs
+++ b/src/array/boolean/mod.rs
@@ -167,7 +167,8 @@ impl BooleanArray {
         let validity = self
             .validity
             .clone()
-            .map(|x| x.slice_unchecked(offset, length));
+            .map(|bitmap| bitmap.slice_unchecked(offset, length))
+            .and_then(|bitmap| (bitmap.unset_bits() > 0).then(|| bitmap));
         Self {
             data_type: self.data_type.clone(),
             values: self.values.clone().slice_unchecked(offset, length),
diff --git a/src/array/fixed_size_binary/mod.rs b/src/array/fixed_size_binary/mod.rs
index ab1a28beb08..d467d2c3c00 100644
--- a/src/array/fixed_size_binary/mod.rs
+++ b/src/array/fixed_size_binary/mod.rs
@@ -131,7 +131,8 @@ impl FixedSizeBinaryArray {
         let validity = self
             .validity
             .clone()
-            .map(|x| x.slice_unchecked(offset, length));
+            .map(|bitmap| bitmap.slice_unchecked(offset, length))
+            .and_then(|bitmap| (bitmap.unset_bits() > 0).then(|| bitmap));
         let values = self
             .values
             .clone()
diff --git a/src/array/fixed_size_list/mod.rs b/src/array/fixed_size_list/mod.rs
index dac5f19c70a..c603f6bf6aa 100644
--- a/src/array/fixed_size_list/mod.rs
+++ b/src/array/fixed_size_list/mod.rs
@@ -150,7 +150,8 @@ impl FixedSizeListArray {
         let validity = self
             .validity
             .clone()
-            .map(|x| x.slice_unchecked(offset, length));
+            .map(|bitmap| bitmap.slice_unchecked(offset, length))
+            .and_then(|bitmap| (bitmap.unset_bits() > 0).then(|| bitmap));
         let values = self
             .values
             .clone()
diff --git a/src/array/list/mod.rs b/src/array/list/mod.rs
index 819f6b1dd20..feb5a5df93b 100644
--- a/src/array/list/mod.rs
+++ b/src/array/list/mod.rs
@@ -222,7 +222,8 @@ impl<O: Offset> ListArray<O> {
         let validity = self
             .validity
             .clone()
-            .map(|x| x.slice_unchecked(offset, length));
+            .map(|bitmap| bitmap.slice_unchecked(offset, length))
+            .and_then(|bitmap| (bitmap.unset_bits() > 0).then(|| bitmap));
         let offsets = self.offsets.clone().slice_unchecked(offset, length + 1);
         Self {
             data_type: self.data_type.clone(),
diff --git a/src/array/map/mod.rs b/src/array/map/mod.rs
index cc8a02c7ccd..51ca56a8459 100644
--- a/src/array/map/mod.rs
+++ b/src/array/map/mod.rs
@@ -167,7 +167,8 @@ impl MapArray {
         let validity = self
             .validity
             .clone()
-            .map(|x| x.slice_unchecked(offset, length));
+            .map(|bitmap| bitmap.slice_unchecked(offset, length))
+            .and_then(|bitmap| (bitmap.unset_bits() > 0).then(|| bitmap));
         Self {
             data_type: self.data_type.clone(),
             offsets,
diff --git a/src/array/primitive/mod.rs b/src/array/primitive/mod.rs
index 2bbdbd05239..a35ae530a2e 100644
--- a/src/array/primitive/mod.rs
+++ b/src/array/primitive/mod.rs
@@ -233,7 +233,8 @@ impl<T: NativeType> PrimitiveArray<T> {
         let validity = self
             .validity
             .clone()
-            .map(|x| x.slice_unchecked(offset, length));
+            .map(|bitmap| bitmap.slice_unchecked(offset, length))
+            .and_then(|bitmap| (bitmap.unset_bits() > 0).then(|| bitmap));
         Self {
             data_type: self.data_type.clone(),
             values: self.values.clone().slice_unchecked(offset, length),
diff --git a/src/array/struct_/mod.rs b/src/array/struct_/mod.rs
index 3fb7be0c7b1..a371147f3d8 100644
--- a/src/array/struct_/mod.rs
+++ b/src/array/struct_/mod.rs
@@ -198,7 +198,8 @@ impl StructArray {
         let validity = self
             .validity
             .clone()
-            .map(|x| x.slice_unchecked(offset, length));
+            .map(|bitmap| bitmap.slice_unchecked(offset, length))
+            .and_then(|bitmap| (bitmap.unset_bits() > 0).then(|| bitmap));
         Self {
             data_type: self.data_type.clone(),
             values: self
diff --git a/src/array/utf8/mod.rs b/src/array/utf8/mod.rs
index dc453a5c37b..2295d9c2439 100644
--- a/src/array/utf8/mod.rs
+++ b/src/array/utf8/mod.rs
@@ -220,7 +220,8 @@ impl<O: Offset> Utf8Array<O> {
         let validity = self
             .validity
             .clone()
-            .map(|x| x.slice_unchecked(offset, length));
+            .map(|bitmap| bitmap.slice_unchecked(offset, length))
+            .and_then(|bitmap| (bitmap.unset_bits() > 0).then(|| bitmap));
         // + 1: `length == 0` implies that we take the first offset.
         let offsets = self.offsets.clone().slice_unchecked(offset, length + 1);
         Self {