Good day,
I have read your requirement, and i can help you to reconcile those large sets of data.
I have worked with sql (ms sql and mysql) enviroments since 18+ years, i work in a web hosting company so i have plenty experience in this field.
If i have understood well, its a millin rows records? Ok, thats fine, work is work and im ready to start right away with this job.
Feel free to contact me.