David Musgrave has a great new post up on Dynamics GP and SQL Server. In it he explains how GP works with SQL Server and why some of the concepts (like dex_row_id) exist.
The Ins and Outs of Dynamics GP on SQL Server
SQL & DataInstall, Upgrade & Admin
Archived post from 2009. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.