Does checking inside a trigger for column updates add any significant overhead? An employee was questioning the extra processing required to check the UPDATE(ColumnName) and I'm wondering what that actually costs in performance.
We have a set of triggers that we use to insert data into audit tables on UPDATE, the audit tables have all the same columns as the original tables plus a couple of info columns, one of them is a varchar(MAX) that stores any column name that was updated on an update. They were all built from the same script and have the same format of:
INSERT INTO audit.OriginalTableName_audit
CASE WHEN UPDATE([col1] THEN '[col1] - ' ELSE '' END +
CASE WHEN UPDATE([col1] THEN '[col1] - ' ELSE '' END + (etc).