An application at the same time may have dozens of thread connection is essentially a database operation, occur every few days there is a probability of a table field update statement is invalid, normal statement execution is not an error, the log is normal record the update statement, but it is not updated, the table records, a few hundred lines and yourself, all the way to update action not use transactions, on the other hand, around 100000 rows in a table data, index, without effective optimization multithreading is updated on the table or the probability of failure will be much higher, such things happen every day a lot of pen, optimization index decreased significantly after a few days in time,