Abstract: Technologies are described for performing database updates in a database environment where the database remains accessible during the updates. For example, a number of database clients may utilize a database environment for running queries or performing transactions. When an update to the database environment needs to be performed (e.g., a change to the database schema), instead of taking the database offline or queueing requests, the database can remain accessible to the database clients throughout the update process. The update process can include switching database connections between a first copy of the database and a second copy of the database that are being replicated. Technologies are also described for performing updates to application code used to interact with the database environment (e.g., alone or in combination with database system updates).