>>Sergey, >> >>>It doesn't apply to EXISTS subqueries because SQL Server doesn't retrieve any data for them. >> >>That is not our experience based on examining the I/Os that occur. I'll see if I can come up with some examples against northwind later tonight. > >Hi David, > >It turned out that I was wrong. See EXISTS Subqueries: SELECT 1 vs. SELECT * >Quote: "The QP will take and expand all *'s early in the pipeline and bind them to objects (in this case, the list of columns). It will then remove unneeded columns due to the nature of the query." >Recomendation: Use something like "SELECT 1 ..."
