Subject frequent update a table, please give me some advise!
Hi, every body!

  I have a problem. Ask everybody to help me.
  I have a table ,The table's DDL is 
  ID integer,
  LastTime timestamp,
  LastReading numeric(12,2),
  Notes varchar(50)
  TableA have about 10,000 rows,  use it to record the last time and the last value of every ID(node), every row was updated once everyday.  After 30 days, perhaps 60 or 80 days.  I can find query this Table become very slowly, just like FB dead or query was freezed.
 After 3-12 hours, the same query(select * from ext_meter ) become very quick.

Please give me some adivses.

Thanks a lot !