fix bux:oceanbase.__tenant_virtual_table_column definition result in ISNULL...

fix bux:oceanbase.__tenant_virtual_table_column definition result in ISNULL fail when rewrite stmt(#977)

src/observer/virtual_table/ob_table_columns.cpp

@@ -265,7 +265,7 @@ int ObTableColumns::fill_row_cells(const ObTableSchema& table_schema, const ObCo
             CS_TYPE_BINARY != column_schema.get_collation_type()) {
           cur_row_.cells_[cell_idx].set_varchar(ObCharset::collation_name(column_schema.get_collation_type()));
         } else {
-          cur_row_.cells_[cell_idx].set_varchar(ObString("NULL"));
+          cur_row_.cells_[cell_idx].set_null();
         }
         cur_row_.cells_[cell_idx].set_collation_type(
             ObCharset::get_default_collation(ObCharset::get_default_charset()));
@@ -329,8 +329,7 @@ int ObTableColumns::fill_row_cells(const ObTableSchema& table_schema, const ObCo
             cur_row_.cells_[cell_idx].set_varchar(ObString(static_cast<int32_t>(pos), buf));
           }
         } else if (def_obj.is_null()) {
-          // NOTICE: default value is NULL need print string "NULL"
-          cur_row_.cells_[cell_idx].set_varchar("NULL");
+          cur_row_.cells_[cell_idx].set_null();
         } else if (def_obj.is_bit()) {
           if (OB_FAIL(def_obj.print_varchar_literal(buf, buf_len, pos, TZ_INFO(session_)))) {
             LOG_WARN("fail to print varchar literal", K(ret), K(def_obj), K(buf_len), K(pos), K(buf));

src/share/inner_table/ob_inner_table_schema.10001_10050.cpp

@@ -464,7 +464,7 @@ int ObInnerTableSchema::tenant_virtual_table_column_schema(ObTableSchema &table_
       MAX_COLLATION_LENGTH, //column_length
       -1, //column_precision
       -1, //column_scale
-      false, //is_nullable
+      true, //is_nullable
       false); //is_autoincrement
   }
 
@@ -509,7 +509,7 @@ int ObInnerTableSchema::tenant_virtual_table_column_schema(ObTableSchema &table_
       COLUMN_DEFAULT_LENGTH, //column_length
       -1, //column_precision
       -1, //column_scale
-      false, //is_nullable
+      true, //is_nullable
       false); //is_autoincrement
   }
 

src/share/inner_table/ob_inner_table_schema.15051_15100.cpp

@@ -282,7 +282,7 @@ int ObInnerTableSchema::tenant_virtual_table_column_ora_schema(ObTableSchema &ta
       MAX_COLLATION_LENGTH, //column_length
       2, //column_precision
       -1, //column_scale
-      false, //is_nullable
+      true, //is_nullable
       false); //is_autoincrement
   }
 
@@ -327,7 +327,7 @@ int ObInnerTableSchema::tenant_virtual_table_column_ora_schema(ObTableSchema &ta
       COLUMN_DEFAULT_LENGTH, //column_length
       2, //column_precision
       -1, //column_scale
-      false, //is_nullable
+      true, //is_nullable
       false); //is_autoincrement
   }
 

src/share/inner_table/ob_inner_table_schema_def.py

@@ -4937,10 +4937,10 @@ def_table_schema(
 
   normal_columns = [
   ('type', 'varchar:COLUMN_TYPE_LENGTH'),
-  ('collation', 'varchar:MAX_COLLATION_LENGTH'),
+  ('collation', 'varchar:MAX_COLLATION_LENGTH', 'true'),
   ('null', 'varchar:COLUMN_NULLABLE_LENGTH'),
   ('key', 'varchar:COLUMN_KEY_LENGTH'),
-  ('default', 'varchar:COLUMN_DEFAULT_LENGTH'),
+  ('default', 'varchar:COLUMN_DEFAULT_LENGTH', 'true'),
   ('extra', 'varchar:COLUMN_EXTRA_LENGTH'),
   ('privileges', 'varchar:MAX_COLUMN_PRIVILEGE_LENGTH'),
   ('comment', 'varchar:MAX_COLUMN_COMMENT_LENGTH'),