Note that null is being used here in the “unknown value” sense in order to combine several possible queries into one query plan. Which is a bad idea for a quer

Note that null is being used here in the “unknown value” sense in order to combine several possible queries into one query plan. Which is a bad idea for a query you need to be performant: $1 can be null (which is possible in the original stackoverflow question that this blog post is a reaction to), and if the parameters are passed in via a bound argument in a prepared statement (not uncommon), then the query plan won't necessarily be taking the passed parameters into account when deciding on the plan.