Microsoft® SQL Server 2012 Unleashed

Row-Overflow Pages

While the maximum in-row size is 8,060 bytes per row, SQL Server 2012 allows actual rows to exceed this size for tables that contain varchar, nvarchar, varbinary, sql_variant, or common language runtime (CLR) user-defined type columns. Although the length of each one of these columns must still fall within the limit of 8,000 bytes (unless you are using the LOB version of these data types), the total combined width of the row is allowed to exceed the 8,060-byte limit.

When a combination of varchar, nvarchar, varbinary, sql_variant, or CLR user-defined type columns exceeds the 8,060-byte limit, SQL Server moves the record column with the largest width to another page in the ROW_OVERFLOW_DATA allocation unit, while maintaining ...