Avoiding table name conflict when multiple delayed job accessing the same database

(1) In application.rb, configure the table name:

config.active_job.queue_adapter = :delayed_job
config.after_initialize do
  Delayed::Backend::ActiveRecord::Job.table_name = 'app_one_delayed_jobs'
end

(2) Create a DB migration to add the "app_one_delayed_jobs" table. It should follow the structure defined by DJ. E.g.

class CreateAppOneDelayedJobs < ActiveRecord::Migration
  def self.up
    create_table :app_one_delayed_jobs, force: true do |table|
      table.integer :priority, default: 0, null: false # Allows some jobs to jump to the front of the queue
      table.integer :attempts, default: 0, null: false # Provides for retries, but still fail eventually.
      table.text :handler,                 null: false # YAML-encoded string of the object that will do work
      table.text :last_error                           # reason for last failure (See Note below)
      table.datetime :run_at                           # When to run. Could be Time.zone.now for immediately, or sometime in the future.
      table.datetime :locked_at                        # Set when a client is working on this object
      table.datetime :failed_at                        # Set when all retries have failed (actually, by default, the record is deleted instead)
      table.string :locked_by                          # Who is working on this object (if locked)
      table.string :queue                              # The name of the queue this job is in
      table.timestamps null: true
    end

    add_index :app_one_delayed_jobs, [:priority, :run_at], name: "app_one_delayed_jobs_priority"
  end

  def self.down
    drop_table :app_one_delayed_jobs
  end
end

(3) Repeat the above steps for other apps.

(4) Execute the DB migrations.

(5) Restart Application and Delayed Job.