PHP applications usually store uploaded files in the server's file system and persist only the file paths in a database. Obtaining a consistent backup of such a dataset may be difficult.
This sample project uses Doctrine ORM to store uploaded files as BLOBs in a database. After all, MySQL supports 4GB BLOBs and PostgreSQL even 4TB BLOBs.
In Doctrine ORM, however, msqli, pdo_mysql and pdo_pgsql do not stream into/from a BLOB
but materialize the BLOB in memory in its entirety.
Therefore, the file size for BLOB storage is limited by the PHP memory_limit (128MB by default),
and for MySQL also by the max_allowed_packet parameter. In order to stay within these
limits, the PHP upload_max_filesize should be set accordingly.
Despite these drawbacks, using BLOBs can be advantageous since this keeps the complete dataset in a single place (the database); this provides for consistent backups and synchronization in a database cluster.
Within this project, a few additional techniques are mentioned that might be useful.
- Uploading files and storing them as BLOBs with Doctrine ORM
- Serving and downloading uploaded files
- Hiding primary keys from clients and identifying file entities by UUID
- Using a mapped superclass as base class for entity classes
- Applying collection per class inheritance to derive specialized file entities (such as image entities)
- Generating image thumbnails with the Imagick PHP extension
- Rendering a UI with the Fluid Template Engine
- Unit testing Doctrine ORM entity classes with PHPUnit