Hints to the query optimizer

- [Narrator] Now let's discuss query optimizer hints. … Hints are suggestions to a query plan builder. … We saw something similar with the enable commands … for different types of join implementations … that I used earlier. … Some databases allow you to specify hints … in line of SQL code using extra SQL statements. … Now this practice pushes the boundaries of … the declarative programing model of SQL. … Some databases support hints inline including Oracle, … EnterpriseDB which is based on Posgres, … MySQL, and SGL server. … Here are some examples of hints used … in various databases. … Note, there's no standard convention, … but there is some overlap between databases. … Postgres uses commands to change the behavior … of the query plan builder. … For example, with the SET enable commands … you can prevent the use of hash joins, … or enable the use of nested loops. … All join options are available by default, … so you don't have to do anything if you want to … have all three enabled. …