pg_stat_statements for where to index

pg_stat_statements.md

Once enabled, it automatically records all queries run against your database and records often and how long they took.

Enable: create extension pg_stat_statements

Note: it has a performance cost to leaving this always on, but it’s pretty small.

SELECT 
  (total_time / 1000 / 60) as total_minutes, 
  (total_time/calls) as average_time, 
  query 
FROM pg_stat_statements 
ORDER BY 1 DESC 
LIMIT 100;