Working with images in WCF

I have a desktop application that needs to upload/download images to/from service computer over TCP Protocol.

At firs开发者_开发问答t, I stored images in file system, but I need to in MS SQL DB to compare which solution is better. Number of images is over half a million. I don't know yet will there be any limitation on size of a photo.

If you have done smth like that, please, write what your opinion upon this question.

Which one is faster, more safe? Which of them works better with this number of photos? If I'll store on DB, do I need to store images apart from all other tables which I use for my application and which type works better - image or varbinary on DB?..and so on.

Thank you.

There's a really good paper by Microsoft Research called To Blob or Not To Blob.

Their conclusion after a large number of performance tests and analysis is this:

• if your pictures or document are typically below 256K in size, storing them in a database VARBINARY column is more efficient

• if your pictures or document are typically over 1 MB in size, storing them in the filesystem is more efficient (and with SQL Server 2008's FILESTREAM attribute, they're still under transactional control and part of the database)

• in between those two, it's a bit of a toss-up depending on your use

If you decide to put your pictures into a SQL Server table, I would strongly recommend using a separate table for storing those pictures - do not store the employee foto in the employee table - keep them in a separate table. That way, the Employee table can stay lean and mean and very efficient, assuming you don't always need to select the employee foto, too, as part of your queries.

For filegroups, check out Files and Filegroup Architecture for an intro. Basically, you would either create your database with a separate filegroup for large data structures right from the beginning, or add an additional filegroup later. Let's call it "LARGE_DATA".

Now, whenever you have a new table to create which needs to store VARCHAR(MAX) or VARBINARY(MAX) columns, you can specify this file group for the large data:

 CREATE TABLE dbo.YourTable
     (....... define the fields here ......)
     ON Data                   -- the basic "Data" filegroup for the regular data
     TEXTIMAGE_ON LARGE_DATA   -- the filegroup for large chunks of data

Check out the MSDN intro on filegroups, and play around with it!

Which version of SQL server? Version 2008 adds FILESTREAM which is specifically designed for this purpose. FILESTREAM data can be located on disk which makes it very fast to access.

If this is not an option, you could look into creating a separate filegroup for your image data (to give you the most flexibility when partitioning your data) and use the varbinary(max) or image data types.

A SQL guru will probably chime in with better info.