Appendix C. Binary data and GridFS

For storing images, thumbnails, audio, and other binary files, many applications rely on the file system only. Although file systems provide fast access to files, file system storage can also can lead to organizational chaos. Consider that most file systems limit the number of files per directory. If you have millions of files to keep track of, then you need to devise a strategy for organizing files into multiple directories. Another difficulty involves metadata. Since the file metadata is still stored in a database, performing an accurate backup of the files and their metadata can be incredibly complicated.

For certain use cases, it may make sense to store files in the database itself because it simplifies file organization and backup. In MongoDB, you can use the BSON binary type to store any kind of binary data. This data type corresponds to the RDBMS BLOB (binary large object) type, and it’s the basis for two flavors of binary object storage provided by MongoDB.