The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/12/runtime-config-query.html Description:
Explanation for random_page_cost is rather outdated, because it did only for case of mechanical hdd. But all modern database servers, which I know, made upon SSD. Do or not do default value for random_page_cost equal to 1 is the question, but, IMHO, at list in the documentation about random_page_cost need to add in a speculation about SSD. It's important because a business programming now is mostly web programming. Most database is poorly designed by web programmer, tables looked like a primary key and a huge json (containing all) with large gin index upon it. Now I am seeing a table with a GIN index 50% of the table size. The database is on SSD, of cause. With default random_page_cost=4 GIN index don't used by planner, but with random_page_cost=1 the result may be not excellent, but acceptable for web programmers.
