From bc9c36f55962ea7e1a1eedbcd15271b1495af149 Mon Sep 17 00:00:00 2001
From: eldenmoon <15605149486@163.com>
Date: Fri, 13 Sep 2024 14:12:06 +0800
Subject: [PATCH] support light schema change

---
 fe/fe-core/src/main/cup/sql_parser.cup        | 22 +++++++++++++++++++
 .../doris/alter/SchemaChangeHandler.java      |  5 +++--
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/fe/fe-core/src/main/cup/sql_parser.cup b/fe/fe-core/src/main/cup/sql_parser.cup
index 29a05856ff3b8e5..98d770d5f9cb4eb 100644
--- a/fe/fe-core/src/main/cup/sql_parser.cup
+++ b/fe/fe-core/src/main/cup/sql_parser.cup
@@ -43,6 +43,7 @@ import org.apache.doris.catalog.PrimitiveType;
 import org.apache.doris.catalog.ScalarType;
 import org.apache.doris.catalog.Type;
 import org.apache.doris.catalog.ArrayType;
+import org.apache.doris.catalog.ComplexVariantType;
 import org.apache.doris.catalog.GeneratedColumnInfo;
 import org.apache.doris.catalog.MapType;
 import org.apache.doris.catalog.StructField;
@@ -814,7 +815,9 @@ nonterminal Expr function_call_expr, array_expr, map_expr;
 nonterminal ArrayLiteral array_literal;
 nonterminal MapLiteral map_literal;
 nonterminal StructField struct_field;
+nonterminal StructField variant_field;
 nonterminal ArrayList<StructField> struct_field_list;
+nonterminal ArrayList<StructField> variant_field_list;
 nonterminal StructLiteral struct_literal;
 nonterminal AnalyticWindow opt_window_clause;
 nonterminal AnalyticWindow.Type window_type;
@@ -6884,6 +6887,8 @@ type ::=
   {: RESULT = new MapType(key_type,value_type); :}
   | KW_STRUCT LESSTHAN struct_field_list:fields GREATERTHAN
   {: RESULT = new StructType(fields); :}
+  | KW_VARIANT LESSTHAN variant_field_list:fields GREATERTHAN
+  {: RESULT = new ComplexVariantType(fields); :}
   | KW_CHAR LPAREN INTEGER_LITERAL:len RPAREN
   {: ScalarType type = ScalarType.createCharType(len.intValue());
      RESULT = type;
@@ -7199,6 +7204,23 @@ struct_field_list ::=
   :}
   ;
 
+variant_field ::=
+  ident:name COLON type:type opt_comment:comment
+  {: RESULT = new StructField(name, type, comment, true); :}
+  ;
+
+variant_field_list ::=
+  variant_field:field
+  {:
+    RESULT = Lists.newArrayList(field);
+  :}
+  | variant_field_list:fields COMMA struct_field:field
+  {:
+     fields.add(field);
+     RESULT = fields;
+  :}
+  ;
+
 struct_literal ::=
   LBRACE expr_list:list RBRACE
   {:
diff --git a/fe/fe-core/src/main/java/org/apache/doris/alter/SchemaChangeHandler.java b/fe/fe-core/src/main/java/org/apache/doris/alter/SchemaChangeHandler.java
index 3051d37527f1075..ae9e2a2c48f37e1 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/alter/SchemaChangeHandler.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/alter/SchemaChangeHandler.java
@@ -611,8 +611,9 @@ private boolean processModifyColumn(ModifyColumnClause alterClause, OlapTable ol
                 if (!col.equals(modColumn)) {
                     typeChanged = true;
                     // TODO:the case where columnPos is not empty has not been considered
-                    if (columnPos == null && col.getDataType() == PrimitiveType.VARCHAR
-                            && modColumn.getDataType() == PrimitiveType.VARCHAR) {
+                    if (columnPos == null && (col.getDataType() == PrimitiveType.VARCHAR
+                            && modColumn.getDataType() == PrimitiveType.VARCHAR)
+                            || (col.getDataType().isVariantType() && modColumn.getDataType().isVariantType())) {
                         col.checkSchemaChangeAllowed(modColumn);
                         lightSchemaChange = olapTable.getEnableLightSchemaChange();
                     }