PostgreSQL has case sensitivity and converts column names to lowercase when trying to do an Active Record Query. An error like the one below will occur:
PG::Error: ERROR: column "some_column" does not exist
LINE 1: SELECT "some_table".* FROM "some_table" WHERE (SOME_UPPERCASE_COLUMN = 'some_value')
In order to solve this problem just escape quotes, likes this:
Class.all(conditions: ["\"SOME_UPPERCASE_COLUMN\" = ?", 'some_value'])
Problem fixed!