Searching for a Data Dictionary for SQL or Oracle

I am looking for metadata specifications (data dictionary) for SQL Server and Oracle databases.

By metadata map, I mean a definitive description of what objects make up database model and their relationships (i.e. a server has 0:n databases, a table has 1:n columns, a column has 0:n constraints).

Any versions of these DBMS platforms would be useful.

I've Community Wiki'd this

Oracle

• Storage can hold multiple databases

• Databases can be opened by multiple instances

• Server can run run multiple instances

• A server can only run a single instace for any given database

• Data is stored in tablespaces

• A tablespace may be made up of multiple data files

• Tables/indexes/Materialized Views can be partitioned across multiple segments

• A segment lives on a tablespace

• A database object (table, index, stored program unit...) is owned by a user

• A table may be be referenced (through a foreign key constraint) by another table, including a table owned by another user

• A table may have at most one primary key constraint

• A table may have zero or more unique constraints

• A primary key or unique constraint is logically enforced by exactly one index (though you could have a multi-column unique constraint which is backed up by multiple unique indexes with the columns in a differing order)

• An index may be unique or non-unique. A unique constraint may be enforced by a unique or non-unique index.

• A table must have at least one column

• Each column has a datatype (and optionally a length or precision/scale)

• A trigger may relate to at most a single table. (Some triggers, such as SERVERERROR, don't relate to a table).

StackExchange Database Administrators Q#1611, answer score: 6