Fix empty default value bug

dbms/src/Debug/MockTiDB.cpp

@@ -97,6 +97,10 @@ ColumnInfo getColumnInfoFromColumn(const NameAndTypePair & column, ColumnID id)
     if (checkDataType<DataTypeUInt64>(nested_type))
         column_info.tp = TiDB::TypeLongLong;
 
+    // Default value.
+    // TODO: Parse default value and set flag properly.
+    column_info.setNoDefaultValueFlag();
+
     return column_info;
 }
 

dbms/src/Storages/Transaction/RegionBlockReader.cpp

@@ -185,8 +185,12 @@ std::tuple<Block, bool> readRegionBlock(const TiDB::TableInfo & table_info,
                     return std::make_tuple(block, false);
 
                 row.emplace_back(Field(column.id));
-                // Fill `zero` value if NOT NULL specified or else NULL.
-                row.push_back(column.defaultValueToField());
+                if (column.hasNoDefaultValueFlag())
+                    // Fill `zero` value if NOT NULL specified or else NULL.
+                    row.push_back(column.hasNotNullFlag() ? GenDecodeRow(column.getCodecFlag()) : Field());
+                else
+                    // Fill default value.
+                    row.push_back(column.defaultValueToField());
             }
 
             // Remove values of non-existing columns, which could be data inserted (but not flushed) before DDLs that drop some columns.