Re: HP uCMDB schema
Perhaps DDMI product is meant here... Indeed, in DDMI the MySQL database schema was fully documented for the reporting (Aggregate) database. DDMI uses the relational database schema and accessing the MySQL database directly is the documented way of accessing the data.
In contrast, UCMDB (and UD) store the data as Configuration Items (CIs), which support class inheritance. The way this is mapped to the relational database schema is not documented (is part of the implementation) and actually evolved over time (between versions). For that reason, the database schema is not documented. One can easily work it out, but it is not recommended to rely on accessing the data directly from the database as the database schema is subject to change and such queries to retrieve the data may be broken in the future. The documented way of accessing data from the UCMDB is via the UCMDB SDK API or via Web Services API.