Good article, and very important.

I noticed some queries only today being executed by very experienced analysts doing awful non-sargable sins like joining a date column to a datetime column, by converting the datetime to a varchar. In the same query they were casting the date column to a varchar in the where clause and comparing it to a string literal.

I thought I was being nice in my pointers on how to improve the query & link to article on sargable queries, but the actuary in question didn't appreciate my advice, stating they were just rerunning another actuary's query. The fact that the query went from 6 minutes to 2 seconds with those very basic changes was beside the point.

On the other hand this person can probably do things with R and SAS that would explode my head, but then, I'm not trying to do those things on their test machine!