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Similarly, a tablespace may service segments for more than one schema. Sometimes it can be used to specify schema so as to form a bond between logical and physical data. By using tablespaces, an administrator also can control the disk layout of an installation. A common use of tablespaces is to optimize performance.
However, Oracle databases store schema objects logically within a tablespace of the database. The data of each object is physically contained in one or more of the tablespace's datafiles . For some objects (such as tables, indexes, and clusters) a database administrator can specify how much disk space the Oracle RDBMS allocates for the object ...
Oracle Database (commonly referred to as Oracle DBMS, Oracle Autonomous Database, or simply as Oracle) is a proprietary multi-model [4] database management system produced and marketed by Oracle Corporation. It is a database commonly used for running online transaction processing (OLTP), data warehousing (DW) and mixed (OLTP & DW) database ...
OID uses standard Oracle database structures to store its internal tables. In Oracle version 9 databases, by default, many Oracle LDAP Table Stores use tablespaces with names beginning with the OLTS_ (and occasionally P1TS_) prefixes. Relevant default schemas used may include ODS (for "Oracle directory server") and ODSCOMMON.
Oracle has its own spin where creating a user is synonymous with creating a schema. Thus a database administrator can create a user called PROJECT and then create a table PROJECT.TABLE. Users can exist without schema objects, but an object is always associated with an owner (though that owner may not have privileges to connect to the database).
The design philosophy behind Oracle Designer and competing tools in the 1980s and 1990s was the Three-schema-architecture that separated an external schema, logical schema and internal schema. For Oracle's product line, the internal schema corresponded to the inner workings of their relational database, the logical schema corresponded to SQL ...
Common examples of DDL statements include CREATE, ALTER, and DROP. If you see a .ddl file, that means the file contains a statement to create a table. Oracle SQL Developer contains the ability to export from an ERD generated with Data Modeler to either a .sql file or a .ddl file.
An example of a database that has not enforced referential integrity. In this example, there is a foreign key (artist_id) value in the album table that references a non-existent artist — in other words there is a foreign key value with no corresponding primary key value in the referenced table.