How to do a left outer join in a eager_load in Rails?

Question

The following query

Install.eager_load(customer: :invoices).includes(calendar_appointment: :technician).where("state = 'scheduled' AND start_time < ?", Date.tomorrow)

Is REALLY slow, I would love to only return the Installs that do not have associated invoices, as that would make it run faster. How would I go about doing that? Also any ideas on improving the speed of this query would be helpful, the appropriate tables are indexed.

Answer 1

Not sure how exactly the association is defined but here's my stab at it:

Install
.joins("inner join invoices on installs.id = invoices.install_id")
.includes(calendar_appointment: :technician)
.where("state = 'scheduled' AND start_time < ? AND invoices.install_id IS NULL", Date.tomorrow)