Data of FI, SRM and R3 in MDM

hi!

here's my question;

what information should i take for the three systems?

what happen if i create the mdm schema with all the fields, and tables that are used in FI, SRM and R3 and create a big repository with one main table of products, and a big subtable of suppliers?

the performance will be affected?

is there any documentation that explains how many subtables you can use? or what to do in this cases?

thanx