SQL Server Query Plans: Startup Expression Predicate

I’ve already posted about predicates in query plans, but here is one more: Startup Expression Predicate. Again, it’s better to illustrate its behavior by example. Let’s create a small table with one clustered index and put some data into it. Now, look at the following query. It should calculate the amount of rows in the … Read more

SQL Server Query Plans: Predicates vs. Seek Predicates

If you have ever written any query with a┬ápredicate, you should have noticed, that, at first, the optimizer is trying to find the smallest indexes, and then try to push predicate down to the get data operators to minimize the amount of logical and physical reads. To illustrate this behavior, let’s look at the example … Read more