The FILESTREAM attribute in SQL Server allows you to store large binary data (like documents, images, or other types of files) directly in the file system while still maintaining transactional consistency with the database. This is particularly useful for large objects (LOBs) that exceed the size limits of traditional data types in SQL Server.
Here’s a guide on how to implement FILESTREAM to store large binary data:
Step 1: Enable FILESTREAM on SQL Server
1. Open SQL Server Configuration Manager.
2. Locate the SQL Server instance that you want to enable FILESTREAM for.
3. Right-click on the instance and select Properties.
4. In the SQL Server Properties dialog, navigate to the FILESTREAM page.
5. Enable the FILESTREAM option and specify a Windows share name if needed.
6. Restart the SQL Server instance for the changes to take effect.
Step 2: Create a Database with FILESTREAM
When creating a database, you need to include a FILESTREAM filegroup.
CREATE DATABASE MyDatabase
ON PRIMARY (
NAME = MyDatabase_Data,
FILENAME = 'C:\Path\To\Your\Data\MyDatabase.mdf'
)
LOG ON (
NAME = MyDatabase_Log,
FILENAME = 'C:\Path\To\Your\Data\MyDatabase.ldf'
)
FILEGROUP MyFileStreamGroup CONTAINS FILESTREAM
(NAME = MyFileStream_Group, FILENAME = 'C:\Path\To\Your\FileStreamData\')
Step 3: Create a Table with a FILESTREAM Column
Now you can create a table that includes a VARBINARY(MAX) column, with the FILESTREAM attribute.
CREATE TABLE MyFiles (
FileID INT PRIMARY KEY IDENTITY(1,1),
FileName NVARCHAR(255) NOT NULL,
FileContent VARBINARY(MAX) FILESTREAM NULL
)
Step 4: Insert Data into the FILESTREAM Column
You can insert binary data (for example, from a file) into the table like so:
-- Insert a file
INSERT INTO MyFiles (FileName, FileContent)
VALUES ('example.txt', 0x<binary_data_here>)
Step 5: Retrieving Data
To retrieve the binary data, just perform a SELECT query:
SELECT FileName, FileContent
FROM MyFiles
WHERE FileID = 1
Step 6: Accessing the FILESTREAM Data
If your FILESTREAM data is stored in a file system, you can access it by mapping to the share specified in the database configuration, or you can also use SQL Server functions to handle it programmatically.
Important Notes
- Ensure that the SQL Server service account has the necessary permissions on the FILESTREAM data file path.
- Implement proper error handling and validation, especially when dealing with large files to ensure integrity.
- FILESTREAM columns can improve performance for large binary data since they are handled as files rather than being stored directly in the database.
Conclusion
Using the FILESTREAM attribute allows you to efficiently manage large binary data in SQL Server while retaining the benefits of transactional integrity. Following the steps above will help you implement and use FILESTREAM successfully in your SQL Server databases.