From c85e3dc8ecc7859cc64594bb91b8de264514b397 Mon Sep 17 00:00:00 2001
From: Luke Manley <lukemanley@gmail.com>
Date: Sat, 1 Mar 2025 14:31:38 -0500
Subject: [PATCH] fix: Categorical min/max panicking when string cache is
 enabled

---
 .../src/chunked_array/ops/aggregate/mod.rs    | 30 +++++++++----------
 .../tests/unit/datatypes/test_categorical.py  |  1 +
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/crates/polars-core/src/chunked_array/ops/aggregate/mod.rs b/crates/polars-core/src/chunked_array/ops/aggregate/mod.rs
index 10e5dc10703d..0a30a45c6b26 100644
--- a/crates/polars-core/src/chunked_array/ops/aggregate/mod.rs
+++ b/crates/polars-core/src/chunked_array/ops/aggregate/mod.rs
@@ -462,7 +462,7 @@ impl CategoricalChunked {
             let rev_map = self.get_rev_map();
             // Fast path where all categories are used
             let c = if self._can_fast_unique() {
-                self.get_rev_map().get_categories().min_ignore_nan_kernel()
+                rev_map.get_categories().min_ignore_nan_kernel()
             } else {
                 // SAFETY:
                 // Indices are in bounds
@@ -475,10 +475,7 @@ impl CategoricalChunked {
             };
             rev_map.find(c.unwrap())
         } else {
-            match self._can_fast_unique() {
-                true => Some(0),
-                false => self.physical().min(),
-            }
+            self.physical().min()
         }
     }
 
@@ -490,7 +487,7 @@ impl CategoricalChunked {
             let rev_map = self.get_rev_map();
             // Fast path where all categories are used
             let c = if self._can_fast_unique() {
-                self.get_rev_map().get_categories().max_ignore_nan_kernel()
+                rev_map.get_categories().max_ignore_nan_kernel()
             } else {
                 // SAFETY:
                 // Indices are in bounds
@@ -503,10 +500,7 @@ impl CategoricalChunked {
             };
             rev_map.find(c.unwrap())
         } else {
-            match self._can_fast_unique() {
-                true => Some((self.get_rev_map().len() - 1) as u32),
-                false => self.physical().max(),
-            }
+            self.physical().max()
         }
     }
 }
@@ -534,14 +528,16 @@ impl ChunkAggSeries for CategoricalChunked {
             DataType::Categorical(r, _) => match self.min_categorical() {
                 None => Scalar::new(self.dtype().clone(), AnyValue::Null),
                 Some(v) => {
-                    let RevMapping::Local(arr, _) = &**r.as_ref().unwrap() else {
-                        unreachable!()
+                    let r = r.as_ref().unwrap();
+                    let arr = match &**r {
+                        RevMapping::Local(arr, _) => arr,
+                        RevMapping::Global(_, arr, _) => arr,
                     };
                     Scalar::new(
                         self.dtype().clone(),
                         AnyValue::CategoricalOwned(
                             v,
-                            r.as_ref().unwrap().clone(),
+                            r.clone(),
                             SyncPtr::from_const(arr as *const _),
                         ),
                     )
@@ -571,14 +567,16 @@ impl ChunkAggSeries for CategoricalChunked {
             DataType::Categorical(r, _) => match self.max_categorical() {
                 None => Scalar::new(self.dtype().clone(), AnyValue::Null),
                 Some(v) => {
-                    let RevMapping::Local(arr, _) = &**r.as_ref().unwrap() else {
-                        unreachable!()
+                    let r = r.as_ref().unwrap();
+                    let arr = match &**r {
+                        RevMapping::Local(arr, _) => arr,
+                        RevMapping::Global(_, arr, _) => arr,
                     };
                     Scalar::new(
                         self.dtype().clone(),
                         AnyValue::CategoricalOwned(
                             v,
-                            r.as_ref().unwrap().clone(),
+                            r.clone(),
                             SyncPtr::from_const(arr as *const _),
                         ),
                     )
diff --git a/py-polars/tests/unit/datatypes/test_categorical.py b/py-polars/tests/unit/datatypes/test_categorical.py
index 229da067f263..00756edc0502 100644
--- a/py-polars/tests/unit/datatypes/test_categorical.py
+++ b/py-polars/tests/unit/datatypes/test_categorical.py
@@ -980,6 +980,7 @@ def test_categorical_prefill() -> None:
 
 
 @pytest.mark.may_fail_auto_streaming  # not implemented
+@pytest.mark.usefixtures("test_global_and_local")
 def test_categorical_min_max() -> None:
     schema = pl.Schema(
         {