Oracle multimedia is tightly integrated into the database. Application development can be greatly simplified when the images and all associated metadata is stored together in the database. Oracle multimedia uses blobs within its type definition, which can be accessed and used as required. In addition, it supports a variety of methods that simplify the act of loading and manipulating digital images. This is covered in greater detail in Chapter 7, Techniques for Creating a Multimedia Database.
Even though the focus should always be to store the images in the database first, this experience is still to be accepted in the marketplace. The attitude is still to store it in the filesystem. Most management when confronted with the idea of putting images in the database invariably come up with the same set of fears that first appeared over ten years ago when database vendors first tried to push the idea of storing images in the database and failed. What's different now is that the rules have changed, the technology has changed and experience has shown that a lot of the previously raised issues are not valid anymore.
Isn't it slower to retrieve an image from the database compared to a filesystem?
This might have been true ten years ago on older disk systems, but with improvements in disk technology this issue has subsequently disappeared. Tests have shown that it is just as fast to retrieve an image from a database as it is from a disk filesystem.
In addition, by using optional caching technology, it is possible to cache frequently accessed images thus improving the time to retrieve them.
Fine grained control over where an image is stored and how it's accessed is possible. A thumbnail can be stored on a local disk and cached in the SGA to ensure the fastest possible speed for retrieval. The original can be stored on lower speed disks. The architecture of the Oracle database is one that inherently supports scalability. This makes it simpler to develop applications that load and deliver images.
Oracle's new Securefile Lobs offer speeds nearly twice as fast as previous versions, for loading and retrieval.
Doesn't it take more storage to put in an image in the database compared to a file system?
Yes it does. The storage format used in the database adds extra overheads to manage locking and to reserve storage for growth. In addition, Oracle puts indexes on images to improve the time it takes to retrieve and manipulate them.
Though there is extra storage required, it is not significant in the overall storage requirements. When tens of thousands of images are stored in the database, the extra required is dwarfed by the overall size of the images. It is also fair to say that disk is cheaper than it once was, and when it comes to database management, the strategy now is to sacrifice storage for performance. When dealing with relational data it is now common practice to add additional indexes and use locally managed tablespaces to improve performance. These extra features come at an additional storage cost. In some cases with data warehouses just for storing relational data, the rule of thumb is to factor in eight times the raw storage to handle all the additional overheads.
So increasing the storage requirements in the database by storing images in it, only ensures that the image data is retrieved optimally and consistently.
Isn't it more complicated and time consuming having to put images into the database and retrieve them compared to a filesystem?
This was exactly the same argument used fifteen years ago when relational databases first appeared. But at that time the argument was concerned with storing data in what was known as flat files versus putting it into a relational database. Time has shown that the overheads of putting data into a relational database offer more benefits and ultimately greater control than when storing it in a flat file. The same argument can be applied to images. Yes there is some programming overhead to put them in, but the advantages gained from having them in the database (as explained previously) is greater than when not having them in the database.
So when it comes to storing and managing those digital assets, keep in mind that ultimately it is easier, safer, and better to keep them stored in a database.
