show slave status\G中的Read_Master_Log_Pos和Relay_Log
usttoclarify,therearethreesetsoffile/positioncoordinatesinSHOWSLAVESTATUS:1)Theposition,ONTHEMASTER,fromwhichtheI/Othreadisreading:Master_Log_File/Read_Master_Log_Pos.-----相对于主库,从库读取主库的二进制日志的位置,是IO线程2