SQL Antipatterns, Volume 1

Solution: In No Particular Order…

The sort-by-random technique is an example of a query that’s bound to perform a table scan and an expensive manual sort. When you design solutions in SQL, you should be on the lookout for inefficient queries like this. Instead of searching fruitlessly for a way to optimize an unoptimizable query, rethink your approach. You can use one of the alternative techniques shown in the following sections to query a random row from a query result set.

Choose a Random Key Value Between MIN and MAX

One technique that avoids sorting the table is to choose a random value between the least primary key value and the greatest primary key value.

Random/soln/rand-min-to-max.sql

​SELECT​ MIN(bug_id), MAX(bug_id) ​ ...