How to look up metadata on different DBMS

From: https://en.wikipedia.org/wiki/Metadata#Database_management Database management Each relational database system has its own mechanisms for storing metadata. Examples of relational-database metadata include:

Tables of all tables in a database, their names, sizes, and number of rows in each table. Tables of columns in each database, what tables they are used in, and the type of data stored in each column.

In database terminology, this set of metadata is referred to as the catalog. The SQL standard specifies a uniform means to access the catalog, called the information schema, but not all databases implement it, even if they implement other aspects of the SQL standard. For an example of database-specific metadata access methods, see Oracle metadata. Programmatic access to metadata is possible using APIs such as JDBC, or SchemaCrawler.

Oracle
Wikipedia regarding Oracle Metadata
 * https://en.wikipedia.org/wiki/Oracle_metadata

O'Reilly on Oracle Metadata
 * http://archive.oreilly.com/pub/a/network/2002/10/28/data_dictionary.html