Do you have a single update or a dataset of updates? SAS provides update options that leave the master table in place (SAS SQL UPDATE and Data step MODIFY), plus more specialized methods. I'd suggest that you start with a SQL UPDATE, but watch out for side conditions (see Hermansen and Legum, SGF 2008).
From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of Harry
Sent: Wednesday, July 15, 2009 10:44 PM
Subject: Updating master table using a reference table
I am trying to update a Master table with values from a reference table.
Given the master table has 12 million observations - what would be the
fastest way of updating?
1) Building a macro list from reference table to update master table?
2) Joining the two tables?