> It is logical for me, since before inserting, it needs to know if
> similar record already exists (to be update). Sso, more operations are
> being done (more disk I/O) compared to a single insert.
>

i was thinging than during an update or insert, the engine try first to
"insert the record" ... and if no error then OK (so exactly like an
insert) and
if an error then at this time try to update the record (and the engine
already know with page to update thank to the previous failed update)

now i know that is not the reality ;)


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