Physical schema

<p>A physical data model (or <a href="/facts/Database_design/Hdb9LRFX">database design</a>) is a representation of a data design as implemented, or intended to be implemented, in a <a href="/facts/Database_management_system/VYcpkevb">database management system</a>. In the <a href="/facts/Project_lifecycle/qo6p4j6Y">lifecycle of a project</a> it typically derives from a <a href="/facts/Logical_data_model/K0EbrogL">logical data model</a>, though it may be <a href="/facts/Reverse-engineer/pmJCV7J7">reverse-engineered</a> from a given <a href="/facts/Database/VYcpkevb">database</a> implementation. A complete physical data model will include all the database artifacts required to create <a href="/facts/Relational_database/pEKGmJLy">relationships between tables</a> or to achieve performance goals, such as <a href="/facts/Index_(database)/TRqmk9It">indexes</a>, constraint definitions, <a href="/facts/Associative_entity/9IXU8WEN">linking tables</a>, <a href="/facts/Partition_(database)/2cKcwmXW">partitioned tables</a> or <a href="/facts/Data_cluster/zDruC5lW">clusters</a>. Analysts can usually use a physical data model to calculate storage estimates; it may include specific storage allocation details for a given database system.
</p><p>As of 2012<a href="https://en.wikipedia.org/w/index.php?title=Physical_schema&action=edit">[update]</a> seven main databases dominate the commercial marketplace: <a href="/facts/Informix_Dynamic_Server/jDdeW93c">Informix</a>, <a href="/facts/Oracle_Database/FHv5g732">Oracle</a>, <a href="/facts/PostgreSQL/LHdXuHfl">Postgres</a>, <a href="/facts/Microsoft_SQL_Server/eCdt2JBL">SQL Server</a>, <a href="/facts/Sybase/2U3d6RUt">Sybase</a>, <a href="/facts/IBM_Db2/2cYITuuY">IBM Db2</a> and <a href="/facts/MySQL/QEEDNBDP">MySQL</a>. Other RDBMS systems tend either to be legacy databases or used within academia such as universities or further education colleges. Physical data models for each implementation would differ significantly, not least due to underlying <a href="/facts/Operating_system/8XTuvMh2"> operating-system</a> requirements that may sit underneath them. For example: SQL Server runs only on <a href="/facts/Microsoft_Windows/bwhAhuSL">Microsoft Windows</a> operating-systems (Starting with SQL Server 2017, SQL Server runs on Linux. It's the same SQL Server database engine, with many similar features and services regardless of your operating system), while Oracle and MySQL can run on Solaris, Linux and other UNIX-based operating-systems as well as on Windows. This means that the disk requirements, security requirements and many other aspects of a physical data model will be influenced by the RDBMS that a <a href="/facts/Database_administrator/3SJoq4ma">database administrator</a> (or an organization) chooses to use.
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Physical schema open-in-new

Physical schema