The Art of SQL Server FILESTREAM - Red Gate Software

Chapter 2: Getting Started with FILESTREAMNote that, after deleting the FILESTREAM column, the table will still be associated withthe FILESTREAM filegroup. Even if you delete all the FILESTREAM columns and tryto drop the FILESTREAM file or filegroup, you will get an error stating that the file orfilegroup is not empty. After dropping all the FILESTREAM columns, you have to setFILESTREAM_ON to NULL, using ALTER TABLE … SET (FILESTREAM_ON = "NULL").If you have created FILESTREAM columns on a table and later on decide to move backto VARBINARY(MAX), you might also want to drop the GUID column you created onthe table. This is relevant in cases where the GUID column was added only to fulfill theFILESTREAM requirement.Tables and FILESTREAM filegroupsEach table that contains FILESTREAM columns must be associated with at least oneFILESTREAM filegroup. A table can be associated with more than one FILESTREAMfilegroup if it is partitioned.As discussed earlier, depending upon your design requirements, all tables can beassociated with a single FILESTREAM filegroup, or they can each be associated witha separate filegroup (or some combination). This decision may be made based on theFILESTREAM load that you expect to have in each table; using separate filegroups candistribute the FILESTREAM I/O load if they are located on different devices.You can specify the FILESTREAM filegroup in which you would like to store theFILESTREAM data when you create a table. If you do not specify the FILESTREAMfilegroup, SQL Server will associate the default FILESTREAM filegroup with that tableand all the FILESTREAM data for that table will be stored there. When a table isassociated with a FILESTREAM filegroup, all the FILESTREAM data from allFILESTREAM columns that exist in that table will go to the same filegroup. It is notpossible to configure two FILESTREAM columns in the same table to store their data intwo separate FILESTREAM filegroups.68