Database refactoring

A database refactoring is a simple change to a <a href="/facts/Database_schema/DBq8fooY">database schema</a> that improves its design while retaining both its behavioral and informational semantics. Database refactoring does not change the way data is interpreted or used and does not fix <a href="/facts/Software_bug/I1uSXySv">bugs</a> or add new functionality. Every refactoring to a database leaves the system in a working state, thus not causing maintenance lags, provided the meaningful data exists in the production environment. 
A database refactoring is conceptually more difficult than a <a href="/facts/Code_refactoring/gkw9oVTE">code refactoring</a>; code refactorings only need to maintain behavioral semantics while database refactorings also must maintain informational semantics.
A database schema is typically refactored for one of several reasons:

<ol><li>To develop the schema in an evolutionary manner in parallel with the evolutionary design of the rest of the system.</li>
<li>To fix design problems with an existing legacy database schema. Database refactorings are often motivated by the desire for <a href="/facts/Database_normalization/uLCKbIBz">database normalization</a> of an existing production database, typically to "clean up" the design of the database.</li>
<li>To implement what would be a large (and potentially risky) change as a series of small, low-risk changes.</li></ol>

Database refactoring open-in-new

Database refactoring