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There is no necessary relationship between schemas and tablespaces: a tablespace can contain objects from different schemas, and the objects for a single schema can reside in different tablespaces. Oracle database specificity does, however, enforce platform recognition of nonhomogenized sequence differentials, which is considered a crucial ...
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.
The import can be made either as an entire foreign schema or merely certain tables belonging to that foreign schema. [188] While support for ISO/IEC 9075-9 bridges the gap between the two competing philosophies surrounding schemas, MySQL and Informix maintain an implicit association between databases while ISO/IEC 9075-9 requires that any such ...
The terms schema matching and mapping are often used interchangeably for a database process. For this article, we differentiate the two as follows: schema matching is the process of identifying that two objects are semantically related (scope of this article) while mapping refers to the transformations between the objects.
This consists of descriptions of (for example) tables, columns, object-oriented classes, and XML tags. The logical schema and conceptual schema are sometimes implemented as one and the same. [2] Physical schema: describes the physical means used to store data. This is concerned with partitions, CPUs, tablespaces, and the like.
They are not to be confused with a database schema—the abstract, structural, organizational specification which defines how every table's data relates to data within other tables. All PostgreSQL database objects, except for a few global objects such as roles and tablespaces, exist within a schema. They cannot be nested, schemas cannot contain ...
The SQL/Schemata, or Information and Definition Schemas, part of the SQL standard is defined by ISO/IEC 9075-11:2008.SQL/Schemata defines the information schema and definition schema, providing a common set of tools to make SQL databases and objects self-describing.
Visual schema/E-R design: the ability to draw entity-relationship diagrams for the database. If missing, the following two features will also be missing; Reverse engineering - the ability to produce an ER diagram from a database, complete with foreign key relationships