SQL Server Team-based Development - Red Gate Software

Chapter 3: Change Management and Source Control
process, so that the source control versions or labels are automatically applied to the
values on the extended property.
Optimistic versus pessimistic source control
There are a couple of prevailing models for managing code within source control. The
older method, used by tools such as Microsoft VSS, is a pessimistic process, wherein the
developer takes an exclusive lock on the code in question through a process known as a
check-out. While a piece of code is checked out, other developers can read the code, but
they cannot edit it themselves. When the original developer is done, the code is checked
back in to VSS and is now available for other developers to use.
Most developers prefer a more flexible, optimistic approach to source control, as offered
by modern source control systems, such as Subversion or Microsoft's Team Foundation
Server. Instead of an exclusive lock, a developer just retrieves a copy of the code and
begins to edit. Other developers are free to also start working with the same code. When
any developer is done with the work, the code is merged back into source control and
committed. This allows for more than one developer to work on any given piece of code,
but still manage the changes so that no one's work is inadvertently overwritten and lost.
Source control systems
There are source control systems available from a large number of vendors, as well as
several open source options. The two source control systems currently supported by Red
Gate SQL Source Control are Microsoft's Team Foundation Server (TFS) and the open
source Subversion (SVN). Microsoft still has Visual SourceSafe (VSS) available, but that is
being retired and will no longer be supported.
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