On 12/13/2012 05:12 PM, AI Rumman wrote:
> Why does the number of rows are different in actual and estimated?
>
Isn't that in the nature of estimates? An estimate is a heuristic guess
at the number of rows it will find for the given query or part of a
query. It's not uncommon for estimates to be out by several orders of
magnitude. Guaranteeing estimates within bounded accuracy and in a given
short amount of time (you don't want your planning time to overwhelm
your execution time) isn't possible.
cheers
andrew
