Oracle 8i introduced the notion of a Virtual Private Database (VPD). A
VPD offers Fine-Grained Access Control (FGAC) for secure separation of
data. This ensures that users only have access to data that pertains to
them. Using this option, one could even store multiple companies' data
within the same schema, without them knowing about it. VPD
configuration is done via the DBMS_RLS (Row Level Security) package.
Select from SYS.V$VPD_POLICY to see existing VPD configuration.