Craig Farrell (10/13/2010)
However, I don't work in the SQL standard. I work in MS SQL Server and T-SQL. Because of that, and because an index can give me performance where a constraint will not, but still takes up the same system space and engine mechanics as a declared index under the hood, I would prefer the index.
Good heavens, has someone introduced a major new performance reducing feature into the MS SQL Server optimiser so that it no longer uses the index that supports a UNIQUE constraint in the way it has used it for at least the last 10 years? That would be horrifying if true :sick: ! But I don't believe it 😀 .
Tom