Although I suspect it will actually be fairly rapid, there's no way to guesstimate such a thing. Create a smaller test of a couple million rows and measure. You should also measure what it may do to your log file.
RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row. First step towards the paradigm shift of writing Set Based code: ________Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column.
"If you think its expensive to hire a professional to do the job, wait until you hire an amateur."--Red Adair
"Change is inevitable... change for the better is not."
When you put the right degree of spin on it, the number 3|8 is also a glyph that describes the nature of a DBAs job. 😉 Helpful Links: How to post code problems Create a Tally Function (fnTally)