Over the years I’ve worked on a number of projects that have shared a common requirement – the ability for users to quickly import large amounts of data into a back end SQL Server database. One such project was a web application used by teachers and other staff members. The software was initially purchased for just two schools in the district, but was soon expanded to encompass other schools. Every few months one or two new schools were brought into the fold; every time a new school was added an administrative user would have to create accounts for the new teachers and staff members so that they could sign into the site. Initially, the application offered a web page for the administrator to create new user accounts one at a time, but this interface quickly became tedious and impractical once larger schools with upwards of 100 users were brought online. To allow school administrators to quickly import new users we created a web page from which a user could upload an Excel spreadsheet that contained the one row for every new user; the columns in the spreadsheet mapped to table columns in the database. After uploading this spreadsheet, the application would walk through each row and insert a record into the table. Through this mechanism an administrator could create the 100+ user accounts by first building an Excel spreadsheet (something many of the schools already had on file) and then upload that spreadsheet. This technique may sound familiar – in Importing an Excel Spreadsheet Using Typed DataSets and TableAdapters , author Nannette Thacker walked through building such an interface. While the described approach works well when importing hundreds of records, it starts to seriously slow down when importing thousands or tens of thousands of records