From 61e838e709fbafbdb7c01d84bcf8c5b7472ad544 Mon Sep 17 00:00:00 2001
From: Nicholas Gates <gatesn@users.noreply.github.com>
Date: Thu, 28 Nov 2024 16:19:04 -0500
Subject: [PATCH] Short-circuit BoolArray null count (#1509)

I believe this is the regression from
https://github.com/spiraldb/vortex/commit/10a1f2172fd70a77c66b6d81d7bb0c8d912dedae

It checks both true_count and null_count, but the null count was
triggering a full stats compute.
---
 vortex-array/src/array/bool/stats.rs | 7 ++++---
 vortex-array/src/stats/statsset.rs   | 3 ++-
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/vortex-array/src/array/bool/stats.rs b/vortex-array/src/array/bool/stats.rs
index 39a3003633..b819be5fdb 100644
--- a/vortex-array/src/array/bool/stats.rs
+++ b/vortex-array/src/array/bool/stats.rs
@@ -43,11 +43,12 @@ impl StatisticsVTable<NullableBools<'_>> for BoolEncoding {
         // Fast-path if we just want the true-count
         if matches!(
             stat,
-            Stat::TrueCount | Stat::Min | Stat::Max | Stat::IsConstant
+            Stat::TrueCount | Stat::Min | Stat::Max | Stat::IsConstant | Stat::NullCount
         ) {
+            let _null_count = array.1.count_set_bits();
             return Ok(StatsSet::bools_with_true_and_null_count(
                 array.0.bitand(array.1).count_set_bits(),
-                array.1.count_set_bits(),
+                array.1.len() - array.1.count_set_bits(),
                 array.0.len(),
             ));
         }
@@ -85,7 +86,7 @@ impl StatisticsVTable<BooleanBuffer> for BoolEncoding {
         // Fast-path if we just want the true-count
         if matches!(
             stat,
-            Stat::TrueCount | Stat::Min | Stat::Max | Stat::IsConstant
+            Stat::TrueCount | Stat::Min | Stat::Max | Stat::IsConstant | Stat::NullCount
         ) {
             return Ok(StatsSet::bools_with_true_and_null_count(
                 buffer.count_set_bits(),
diff --git a/vortex-array/src/stats/statsset.rs b/vortex-array/src/stats/statsset.rs
index bea81aaf62..0c2b12ed65 100644
--- a/vortex-array/src/stats/statsset.rs
+++ b/vortex-array/src/stats/statsset.rs
@@ -90,9 +90,10 @@ impl StatsSet {
         true_count: usize,
         null_count: usize,
         len: usize,
-    ) -> StatsSet {
+    ) -> Self {
         StatsSet::from_iter([
             (Stat::TrueCount, true_count.into()),
+            (Stat::NullCount, null_count.into()),
             (Stat::Min, (true_count == len).into()),
             (Stat::Max, (true_count > 0).into()),
             (