>>>>> "Kelly" == Kelly Yancey <kbyanc@stripped> writes:
Kelly> I recall reading a week or so ago on this list that if you wanted to
Kelly> update a table but not update the first timestamp value, the solution was
Kelly> to simply set the field equal to itself as part of the update.
Kelly> This makes sense, however I'm curious as to the efficiency of this
Kelly> approach?
Kelly> Does mysql realize the value isn't changing and not update the field at
Kelly> all (like it optimizes other UPDATEs). Or does it first update the
Kelly> timestamp like it does normally and then set it to the original value (I
Kelly> have trouble seeing the latter happening).
Kelly> Needless to say, I'm hoping it is the first because then we know there
Kelly> is no overhead in not updating a timestamp field (other than the miniscule
Kelly> amount required to process the additional field in the UPDATE query).
Hi!
In the case of:
SET timestamp_colum=timestamp_column
You will only loose a memcpy() of size of the timestamp column (4
bytes) + some setup. I don't think you will notice this...
Regards,
Monty
