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Explanation for random_page_cost is rather outdated, because it did only for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.