How is the serial desired memory calculated for this estimated plan

GokhanVarol 2014-08-20 18:10:17

The attached estimated plan has a serial desired memory over 200GB, how is this value calculated?

Aaron Bertrand 2014-08-20 18:27:40
I don't know the exact memory calculations, but take a look at the estimated data size in the tooltip for several operators, most notably the 18.3% hash match that's trying to process almost 1.3 billion rows. There's 234 GB right there…
GokhanVarol 2014-08-20 18:36:57
Yes the dataflows are quite large but I thought the hash table was built on the top input. For 3 hash joins the top inputs from left to right are about <10GB, <13GB, <5.5GB which adds up to less than 30GB.
SQLkiwi 2014-08-20 21:46:07
Can you share a post-execution (actual) plan please?