Checksum-Based Storage Implementation
The following sections provide more information on how checksum-based storage features are implemented in Artifactory.
Artifactory stores any binary file only once. This is what we call "once and once only storage". First time a file is uploaded, Artifactory runs the required checksum calculations when storing the file, however, if the file is uploaded again (to a different location, for example), the upload is implemented as a simple database transaction that creates another record mapping the file's checksum to its new location. There is no need to actually store the file again in storage. No matter how many times a file is uploaded, the filestore only hosts a single copy of the file.
Copying and Moving Files
Copying and moving a file is implemented by simply adding and removing database references and, correspondingly, performance of these actions is that of a database transaction.
Deleting a file is also a simple database transaction in which the corresponding database record is deleted. The file itself is not directly deleted, even if the last database entry pointing to it is removed. So-called "orphaned" files are removed in the background by Artifactory's garbage collection processes.
Upload, Download, and Replication
Before moving files from one location to another, Artifactory sends checksum headers. If the files already exist in the destination, they are not transferred even if they exist under a different path.
Filesystem performance is greatly improved because actions on the filestore are implemented as database transactions, so there is never any need to do a write-lock on the filesystem.
Searching for a file by its checksum is extremely fast since Artifactory is actually searching through the database for the specified checksum.
Since the database is a layer of indirection between the filestore and the displayed layout, any layout can be supported, whether for one of the standard packaging formats such as Maven1, Maven2, npm, NuGet etc. or for any custom layout.