DB design for a multible company accounting system

[Sebastian Mayer]

Hello,

i want to design a multible company accounting system with the following parameters.

2000 companies
20 tables per company
max table has 4 M rows (but only 3 tables are so big)

the different companies are totaly separated, i. e. no query will touch 2 different companies.

So I wonder if it is better to:
- create 20 tables for every company (40.000 tables), for example table "openItem1222"
- using partitioning with companyId as separator
- only split the 3 big tables (6000 + 17 tables)
- just use 20 tables with companyId as part of key

Thank you very much for your recommendations
Sebastian