The Art of SQL Server FILESTREAM - Red Gate Software

Chapter 3: Accessing FILESTREAM Data from Client Applications• FileAccess – This parameter specifies the required file access mode. The possiblevalues are:• FileAccess.Read – Opens the FILESTREAM data file for reading. The file pointeris placed at the beginning of the file.• FileAccess.Write – Opens the FILESTREAM data file for writing.• FileAccess.ReadWrite – Opens the FILESTREAM data file for reading andwriting. The file pointer is placed at the beginning of the file. You can use theSeek() method to move the file pointer to specific locations in the file and makepartial updates, or to move to the end of the file to append content.SqlFileStream provides another version of the constructor that gives morecontrol over the FILESTREAM data file being opened. Listing 3-35 shows an examplethat demonstrates the advanced SqlFileStream constructor.// Open and read file using SqlFileStream ClassSqlFileStream fs = new SqlFileStream(filePath, txContext, FileAccess.Read,FileOptions.SequentialScan, 0);Listing 3-35:Using the advanced FILESTREAM constructor.This version of the SqlFileStream constructor allows you to specify more optionswhen opening the FILESTREAM data file. The additional parameters enable you tooptimize the FILESTREAM operations.The first three parameters are the same as for the basic FILESTREAM constructor whichwe discussed earlier. The FileOptions parameter enables you to specify additional flagsthat inform the system about your intended file access pattern and optimize the operationsaccordingly. For example, Listing 3-35, above, tells the system that you intend to usethe file sequentially; the system uses this information to optimize FILESTREAM accessbecause it knows in advance that you will not move the file pointer backwards or jumpinto a random location in the file.124