From ba19832befc796f362ee5214c13d6176235988d7 Mon Sep 17 00:00:00 2001
From: Thinh Bui <thinh.ducbui@gmail.com>
Date: Fri, 23 Aug 2024 16:49:44 -0700
Subject: [PATCH 1/2] fix concat bug

---
 .../expr-common/src/type_coercion/binary.rs   |  3 ++
 .../sqllogictest/test_files/type_coercion.slt | 29 +++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/datafusion/expr-common/src/type_coercion/binary.rs b/datafusion/expr-common/src/type_coercion/binary.rs
index 401762ad4d36..0fa87655ffc6 100644
--- a/datafusion/expr-common/src/type_coercion/binary.rs
+++ b/datafusion/expr-common/src/type_coercion/binary.rs
@@ -936,6 +936,9 @@ fn string_concat_coercion(lhs_type: &DataType, rhs_type: &DataType) -> Option<Da
         (LargeUtf8, from_type) | (from_type, LargeUtf8) => {
             string_concat_internal_coercion(from_type, &LargeUtf8)
         }
+        (Dictionary(_, lhs_value_type), Dictionary(_, rhs_value_type)) => {
+            string_coercion(&lhs_value_type, &rhs_value_type).or(None)
+        }
         _ => None,
     })
 }
diff --git a/datafusion/sqllogictest/test_files/type_coercion.slt b/datafusion/sqllogictest/test_files/type_coercion.slt
index e420c0cc7155..0f9399cede2e 100644
--- a/datafusion/sqllogictest/test_files/type_coercion.slt
+++ b/datafusion/sqllogictest/test_files/type_coercion.slt
@@ -50,6 +50,35 @@ select interval '1 month' - '2023-05-01'::date;
 query error DataFusion error: Error during planning: Cannot coerce arithmetic expression Interval\(MonthDayNano\) \- Timestamp\(Nanosecond, None\) to valid types
 SELECT interval '1 month' - '2023-05-01 12:30:00'::timestamp;
 
+# dictionary(int32, utf8) -> utf8
+query T
+select arrow_cast('foo', 'Dictionary(Int32, Utf8)') || arrow_cast('bar', 'Dictionary(Int32, Utf8)');
+----
+foobar
+
+# dictionary(int32, largeUtf8) -> largeUtf8
+query T
+select arrow_cast('foo', 'Dictionary(Int32, LargeUtf8)') || arrow_cast('bar', 'Dictionary(Int32, LargeUtf8)');
+----
+foobar
+
+####################################
+## Concat column dictionary test  ##
+####################################
+statement ok
+create table t as values (arrow_cast('foo', 'Dictionary(Int32, Utf8)'), arrow_cast('bar', 'Dictionary(Int32, Utf8)'));
+
+query T
+select column1 || column2 from t;
+----
+foobar
+
+statement ok
+DROP TABLE t
+
+#######################################
+## Concat column dictionary test end ##
+#######################################
 
 ####################################
 ## Test type coercion with UNIONs ##

From 946705120c0ae4c274c1419ed676e2c9721e8df9 Mon Sep 17 00:00:00 2001
From: Thinh Bui <thinh.ducbui@gmail.com>
Date: Fri, 23 Aug 2024 18:54:48 -0700
Subject: [PATCH 2/2] clippy fix

---
 datafusion/expr-common/src/type_coercion/binary.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/datafusion/expr-common/src/type_coercion/binary.rs b/datafusion/expr-common/src/type_coercion/binary.rs
index 0fa87655ffc6..552bc89b38f4 100644
--- a/datafusion/expr-common/src/type_coercion/binary.rs
+++ b/datafusion/expr-common/src/type_coercion/binary.rs
@@ -937,7 +937,7 @@ fn string_concat_coercion(lhs_type: &DataType, rhs_type: &DataType) -> Option<Da
             string_concat_internal_coercion(from_type, &LargeUtf8)
         }
         (Dictionary(_, lhs_value_type), Dictionary(_, rhs_value_type)) => {
-            string_coercion(&lhs_value_type, &rhs_value_type).or(None)
+            string_coercion(lhs_value_type, rhs_value_type).or(None)
         }
         _ => None,
     })