Computed Column Performance in SQL Server


 

SQL Server computed columns provide a handy tool for building expressions into table definitions. Still, they can also lead to performance woes, especially as expressions become more complex, applications more demanding, and data sets grow larger by the minute.

A computed column is a virtual column whose value is calculated from other values in the table. By default, the expression’s outputted value is not physically stored. Instead, SQL Server runs the expression when the column is queried and returns the value as part of the result set. Although this puts more burden on the processor, it also reduces the amount