Subject RE: frequent update a table, please give me some advise!
>Hi Jimmy! 

>Please tell us more if you want an accurate answer to your problem. The two options that I think of, is: 
  Sorry, the table Ext_Meter has 100,000 rows, all of rows have been updated once everyday.  
  However,  it appears that the query (select * from ext_meter) has been freezed once every 2 or 3 months.

 I set sweep interval to 0 and I did not run sweep.  
>a) a long running transaction holding up transaction counters. Use gstat to see if the gap between 
>oldest (active) and next transaction is big (if this is the case, you would normally observe that many 
>selects ran slow). 
 when select ext_meter was freezed, it seemed that other selects ran normally. 

>b) If you're using a transaction with lock resolution WAIT and another transaction has uncommitted 
>changes to a record you are trying to modify. Try changing to NO WAIT or set a shorter LOCK 
>TIMEOUT to see if you get an error message rather than things appearing to hang (normally, this 
>should only happen if you UPDATE something, not if you only do SELECT). 
  I will check if I have used WAIT or not.

>Probably, there could be other reasons as well.