[ibd2sql] mysql做过online ddl(instant)的数据应该怎么解析?

# ROW VERSION/COLUMN_COUNT判断
if self.table.mysqld_version_id < 80029 and self.table.mysqld_version_id >=80012 and rheader.instant_flag:
  _COLUMN_COUNT = self._read_innodb_varsize()
elif if rheader.row_version_flag:
  ROW_VERSION = self._read_innodb_varsize()

# NULL BITMASK计算
for _phno,colno in self.table.column_ph:
 col = self.table.column[colno]
 if rheader.row_version_flag:
    if (ROW_VERSION >= col['version_added'] and (col['version_dropped'] == 0 or col['version_dropped'] > ROW_VERSION)) or (col['version_dropped'] > ROW_VERSION and ROW_VERSION >= col['version_added']):
       null_bitmask_count += 1 if col['is_nullable'] else 0
    else:
       null_bitmask_count += 1 if col['is_nullable'] else 0

# 读取索引(注意前缀索引问题)
                        if self.haveindex: #有索引的时候
                                for colno,prefix_key,order in self.table.index[self.idxno]['element_col']:
                                        col = self.table.column[colno]
                                        self.debug(f"\tREAD KEY COLNO:{colno} NAME:{col['name']}")

                                        #pk 不需要判断null
                                        if prefix_key == 0:
                                                _data[colno],_expage[colno] = self._read_field(col)
                                                col_count -= 1
                                                self.debug(f"\tREAD KEY NO:{colno} NAME:{col['name']} FINISH. VALUES: {_data[colno]}")
                                        else:
                                                _,__ = self._read_field(col)
                                                self.debug(f'前缀索引数据为: {_} . SKIP IT.' )

                        else:
                                self.debug("\tNO CLUSTER KEY.WILL READ 6 bytes(ROWID)",)
                                _row_id = self._read_uint(6) #ROW_ID
                                self.debug(f"\t ROW_ID:{_row_id}")
 
# 读取TRX&ROLLPTR
_row['trx'] = self._read_uint(6)
_row['rollptr'] = self._read_uint(7)

# 读取数据. 存在多种条件
      for _phno,colno in self.table.column_ph:
        if colno in _data: # KEY
          continue
        col = self.table.column[colno]
        self.debug(f"\tNAME: {col['name']}  VERSION_ADDED:{col['version_added']}  VERSION_DROPED:{col['version_dropped']} COL_INSTANT:{col['instant']} ROW VERSION:{ROW_VERSION}")
        if rheader.row_version_flag: # >=8.0.29 的online ddl
          if (ROW_VERSION >= col['version_added'] and (col['version_dropped'] == 0 or col['version_dropped'] > ROW_VERSION)) or (col['version_dropped'] > ROW_VERSION and ROW_VERSION >= col['version_added']):
            if col['is_nullable']:
              _nullable_count += 1
            if col['is_nullable'] and null_bitmask&(1<<_nullable_count):
              _data[colno],_expage[colno] = None,None
              self.debug(f"######## DDCW FLAG 1 ########")
            else:
              _data[colno],_expage[colno] = self._read_field(col)
              self.debug(f"######## DDCW FLAG 2 ########")
          elif ROW_VERSION < col['version_added']:
            _data[colno] = col['default'] if not col['instant_null'] else None
            _expage[colno] = None
            self.debug(f"######## DDCW FLAG 3 ########")
          #elif col['version_dropped'] <= ROW_VERSION:
          else:
            _data[colno],_expage[colno] = None,None
            self.debug(f"######## DDCW FLAG 4 ########")
        elif ( not rheader.instant_flag and col['instant']): # 8.0.12-28 的online ddl
          self.debug(f'mysql 8.0.12-28 版本的add column (instant) 读默认值 (实际版本:{self.table.mysqld_version_id}) ')
          _data[colno] = col['default'] if not col['instant_null'] else None
          _expage[colno] = None
          self.debug(f"######## DDCW FLAG 5 ########")
        elif not rheader.instant and col['version_dropped'] > 0: # 删除的字段就不读了(无instant情况下)
          _data[colno],_expage[colno] = None,None
          self.debug(f"######## DDCW FLAG 6 ########")
        #elif col['instant'] and rheader.instant_flag:
        else:
          #self.debug(f"NULLABLE {col['name']}:  is_nullable:{col['is_nullable']} null_bitmask:{null_bitmask} _nullable_count:{_nullable_count}")
          if col['is_nullable']:
            _nullable_count += 1
          if col['is_nullable'] and null_bitmask&(1<<_nullable_count):
            _data[colno],_expage[colno] = None,None
            self.debug(f"######## DDCW FLAG 7 ########")
          else:
            _data[colno],_expage[colno] = self._read_field(col)
            self.debug(f"######## DDCW FLAG 8 ########")