Question

i’m processing a form that has a lot of fields for a user who is editing an existing record. the user may have only changed one field, and i would typically do an update query that sets the values of all the fields, even though most of them don’t change. i could do some sort of tracking to see which fields have actually changed, and only update the few that did. is there a performance difference between updating all fields in a record vs only the one that changed? are there other reasons to go with either method? the shotgun method is pretty easy…

Answer 1

I would say that it depends upon the following:

• The size of the data that is being
  processed
• The location of the database server
  relative to the application
• The time taken to complete any checks
  for data change

If you are transferring large amounts of data and/or the connection is remote then you should do some tests to see if you can improve performance by tracking changes. Otherwise, you will probably find that it is negligible presuming that one record is being manipulated.