Often, DBAs need to load copious amounts of data quickly — whether it's a nightly data load or a conversion from comma-delimited text files. When a few hundred megabytes of data need to get into SQL Server in a limited time frame, a bulk operation is the way to get the heavy lifting done.
XML's popularity may be growing, but its file sizes seem to be growing even faster. XML's data tags add significant bloat to a data file, sometimes quadrupling the file size or more. For large files, IT organizations are sticking with CSV (also known as comma-delimited) files. For these old standby files, the best way to insert that data is using a bulk operation.
In SQL Server, bulk operations pump data directly to the data file according to the following models: