???????????????????裺
????1. ??????????????
?????????????????????????sql???????????????????????????????????￡?
????1. show variables like '%slow_query_log%'; ?????????????????????
????2. set global slow_query_log=1;  ??????????????
????2. ??explain ????sql ???
????ps: explain  select *  from temp ?????????????

??????????????????????????????????????? ????????????????(type??key??ref??extra).????????type?all??????????sql????????????????key???????sql?????????????????null??????С?ref ??????????????????Щ??????
????????const??????????Extra ????Щ??????????????using index??using filesort???????????????????????
??????????β???????????????  ???id??????????????С????id???id???????С?
????3. ???profile  ????sql ??????????????sql?????????????е???????????
????1. set profiling=1; ????profile ????????2. show profiles?? ??????mysql ????????????

????3.show profile for query id;
???????磺show profile for query 2; ?? ?? ?????sql ??????????????

????4. ???mysql ??????????????????????????DBA ?????????
???????????????????mysql??????????????????ò???????????С????