[fix](schema-change) Nested types should only support enlarging varchar length with light schema change

fe/fe-core/src/main/java/org/apache/doris/catalog/ColumnType.java

@@ -103,6 +103,7 @@ public abstract class ColumnType {
         schemaChangeMatrix[PrimitiveType.VARCHAR.ordinal()][PrimitiveType.DATEV2.ordinal()] = true;
         schemaChangeMatrix[PrimitiveType.VARCHAR.ordinal()][PrimitiveType.STRING.ordinal()] = true;
         schemaChangeMatrix[PrimitiveType.VARCHAR.ordinal()][PrimitiveType.JSONB.ordinal()] = true;
+        // could not change varchar to char cuz varchar max length is larger than char
 
         schemaChangeMatrix[PrimitiveType.STRING.ordinal()][PrimitiveType.JSONB.ordinal()] = true;
 
@@ -196,7 +197,10 @@ public static void checkForTypeLengthChange(Type src, Type dst) throws DdlExcept
     // return true if the checkType and other are both char-type otherwise return false,
     // which used in checkSupportSchemaChangeForComplexType
     private static boolean checkSupportSchemaChangeForCharType(Type checkType, Type other) throws DdlException {
-        if (checkType.isStringType() && other.isStringType()) {
+        if (checkType.getPrimitiveType() == PrimitiveType.VARCHAR
+                && other.getPrimitiveType() == PrimitiveType.VARCHAR) {
+            // currently nested types only support light schema change for internal fields, for string types,
+            // only varchar can do light schema change
             checkForTypeLengthChange(checkType, other);
             return true;
         } else {
@@ -273,7 +277,8 @@ public static void checkSupportSchemaChangeForComplexType(Type checkType, Type o
             // only support char-type schema change behavior for nested complex type
             // if nested is false, we do not check return value.
             if (nested && !checkSupportSchemaChangeForCharType(checkType, other)) {
-                throw new DdlException("Cannot change " + checkType.toSql() + " to " + other.toSql());
+                throw new DdlException(
+                        "Cannot change " + checkType.toSql() + " to " + other.toSql() + " in nested types");
             }
         }
     }

regression-test/data/schema_change_p0/test_type_length_change.out

@@ -16,6 +16,6 @@
 
 -- !master_sql --
 k	int	Yes	true	\N	
-c0	varchar(6)	Yes	true	\N	
-c1	varchar(6)	Yes	true	\N	
+c0	varchar(6)	Yes	false	\N	NONE
+c1	varchar(6)	Yes	false	\N	NONE
 

regression-test/suites/schema_change_p0/test_type_length_change.groovy

@@ -24,7 +24,8 @@ suite("test_type_length_change", "p0") {
             k INT,
             c0 CHAR(5),
             c1 VARCHAR(5)
-        )
+        ) DUPLICATE KEY (k)
+        DISTRIBUTED BY HASH(k) BUCKETS 1
         PROPERTIES ( "replication_allocation" = "tag.location.default: 1");
     """
 
@@ -74,4 +75,9 @@ suite("test_type_length_change", "p0") {
     sql """  INSERT INTO ${tableName} VALUES(4, "abcde", "abcde") """
     qt_master_sql """ SELECT * FROM ${tableName} ORDER BY k"""
     qt_master_sql """ DESC ${tableName} """
+
+    test {
+        sql """ ALTER TABLE ${tableName} MODIFY COLUMN c1 CHAR(10) """
+        exception "Can not change VARCHAR to CHAR"
+    }
 }

regression-test/suites/schema_change_p0/test_varchar_sc_in_complex.groovy

@@ -477,6 +477,61 @@ suite ("test_varchar_sc_in_complex") {
 //            """
 //        qt_sc_after " select * from there_level_nested_type order by c0; "
 
+        // case7. do not support enlarge char length in nested types
+        def tableName2 = "test_enlarge_char_length_nested"
+        sql """ DROP TABLE IF EXISTS ${tableName2} """
+        sql """
+            CREATE TABLE IF NOT EXISTS ${tableName2}
+            (
+                k BIGINT NOT NULL,
+                c1 ARRAY<CHAR(10)>,
+                c2 MAP<CHAR(10), CHAR(10)>,
+                c3 STRUCT<col:CHAR(10)>,
+                c4 ARRAY<VARCHAR(10)>,
+                c5 MAP<VARCHAR(10), VARCHAR(10)>,
+                c6 STRUCT<col:VARCHAR(10)>
+            ) DISTRIBUTED BY HASH(k) BUCKETS 1
+              PROPERTIES ( "replication_num" = "1", "light_schema_change" = "true" );
+        """
+        test {
+            sql """ ALTER TABLE ${tableName2} MODIFY COLUMN c1 ARRAY<CHAR(20)> """
+            exception "Cannot change char(10) to char(20) in nested types"
+        }
+        test {
+            sql """ ALTER TABLE ${tableName2} MODIFY COLUMN c2 MAP<CHAR(20), CHAR(20)> """
+            exception "Cannot change char(10) to char(20) in nested types"
+        }
+        test {
+            sql """ ALTER TABLE ${tableName2} MODIFY COLUMN c3 STRUCT<col:CHAR(20)> """
+            exception "Cannot change char(10) to char(20) in nested types"
+        }
+
+        // case8. do not support convert from char to varchar and varchar to char in nested types
+        test {
+            sql """ ALTER TABLE ${tableName2} MODIFY COLUMN c1 ARRAY<VARCHAR(20)> """
+            exception "Cannot change char(10) to varchar(20) in nested types"
+        }
+        test {
+            sql """ ALTER TABLE ${tableName2} MODIFY COLUMN c2 MAP<VARCHAR(20), VARCHAR(20)> """
+            exception "Cannot change char(10) to varchar(20) in nested types"
+        }
+        test {
+            sql """ ALTER TABLE ${tableName2} MODIFY COLUMN c3 STRUCT<col:VARCHAR(20)> """
+            exception "Cannot change char(10) to varchar(20) in nested types"
+        }
+
+        test {
+            sql """ ALTER TABLE ${tableName2} MODIFY COLUMN c4 ARRAY<CHAR(20)> """
+            exception "Cannot change varchar(10) to char(20) in nested types"
+        }
+        test {
+            sql """ ALTER TABLE ${tableName2} MODIFY COLUMN c5 MAP<CHAR(20), CHAR(20)> """
+            exception "Cannot change varchar(10) to char(20) in nested types"
+        }
+        test {
+            sql """ ALTER TABLE ${tableName2} MODIFY COLUMN c6 STRUCT<col:CHAR(20)> """
+            exception "Cannot change varchar(10) to char(20) in nested types"
+        }
     } finally {
          try_sql("DROP TABLE IF EXISTS ${tableName}")
     }