From e60ecf91d18fc3a818547dc7441607e1f52c69f4 Mon Sep 17 00:00:00 2001
From: Hu Shenggang <hushenggang@selectdb.com>
Date: Tue, 2 Dec 2025 14:59:13 +0800
Subject: [PATCH] [fix](olap) Fix the crash in column pruning caused by the
 light schema change

---
 .../olap/rowset/segment_v2/column_reader.cpp  |  2 ++
 .../complex_types/test_pruned_columns.out     |  4 +++
 .../complex_types/test_pruned_columns.groovy  | 33 +++++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/be/src/olap/rowset/segment_v2/column_reader.cpp b/be/src/olap/rowset/segment_v2/column_reader.cpp
index 8e3962236fef63..72e46848861fc1 100644
--- a/be/src/olap/rowset/segment_v2/column_reader.cpp
+++ b/be/src/olap/rowset/segment_v2/column_reader.cpp
@@ -20,6 +20,7 @@
 #include <assert.h>
 #include <gen_cpp/Descriptors_types.h>
 #include <gen_cpp/segment_v2.pb.h>
+#include <glog/logging.h>
 
 #include <algorithm>
 #include <memory>
@@ -888,6 +889,7 @@ Status ColumnReader::new_struct_iterator(ColumnIteratorUPtr* iterator,
         TabletColumn column = tablet_column->get_sub_column(i);
         ColumnIteratorUPtr it;
         RETURN_IF_ERROR(Segment::new_default_iterator(column, &it));
+        it->set_column_name(column.name());
         sub_column_iterators.emplace_back(std::move(it));
     }
 
diff --git a/regression-test/data/datatype_p0/complex_types/test_pruned_columns.out b/regression-test/data/datatype_p0/complex_types/test_pruned_columns.out
index 870a576307486f..86728bafd1ca8d 100644
--- a/regression-test/data/datatype_p0/complex_types/test_pruned_columns.out
+++ b/regression-test/data/datatype_p0/complex_types/test_pruned_columns.out
@@ -29,3 +29,7 @@
 0.41
 0.99
 
+-- !sql8 --
+\N
+added_z
+
diff --git a/regression-test/suites/datatype_p0/complex_types/test_pruned_columns.groovy b/regression-test/suites/datatype_p0/complex_types/test_pruned_columns.groovy
index d54d924e97fdc9..c2a7e2b71466c1 100644
--- a/regression-test/suites/datatype_p0/complex_types/test_pruned_columns.groovy
+++ b/regression-test/suites/datatype_p0/complex_types/test_pruned_columns.groovy
@@ -85,4 +85,37 @@ suite("test_pruned_columns") {
     qt_sql7 """
         select struct_element(dynamic_attributes['theme_preference'], 'confidence_score') from `tbl_test_pruned_columns_map` order by id;
     """
+
+    // test light schema change with nested complex types
+    sql """
+        DROP TABLE IF EXISTS nested_sc_tbl;
+        CREATE TABLE nested_sc_tbl (
+            `id` BIGINT,
+            `s_info` STRUCT<a:INT, b:VARCHAR(20)>,
+            `arr_s` ARRAY<STRUCT<x:INT, y:INT>>,
+            `map_s` MAP<VARCHAR, STRUCT<m:INT, n:FLOAT>>
+        ) 
+        UNIQUE KEY(`id`) 
+        DISTRIBUTED BY HASH(`id`) BUCKETS 4 
+        PROPERTIES (
+            "replication_num" = "1",
+            "light_schema_change" = "true" 
+        );
+    """
+    sql """
+        ALTER TABLE nested_sc_tbl  MODIFY COLUMN s_info STRUCT<a:INT, b:VARCHAR(25), c:INT>;
+    """
+    sql """
+        INSERT INTO nested_sc_tbl VALUES (1, struct(10, 'v1_struct', 100), array(struct(100, 200)), map('k1', struct(1, 1.1)));
+    """
+    sql """
+        ALTER TABLE nested_sc_tbl MODIFY COLUMN arr_s ARRAY<STRUCT<x:INT, y:INT, z:VARCHAR(10)>>;
+    """
+    sql """
+        INSERT INTO nested_sc_tbl VALUES (3, struct(30.5, 'v3', 888), array(struct(500, 600, 'added_z'), struct(501, 601, 'added_z_2')), map('k3', struct(3, 3.3)));
+    """
+
+    qt_sql8 """
+        select struct_element(element_at(arr_s, 1), 'z') as inner_z FROM nested_sc_tbl ORDER BY id;
+    """
 }
\ No newline at end of file