Instructions for migrating from shared database to dedicated database on Heroku

Before you start the migration please be aware of these facts:

• Heroku doesn’t migrate the data from the shared database to the dedicated database automatically.
• Heroku doesn’t assign the dedicated database as the primary database automatically.
• Heroku doesn’t remove the shared database even after you complete the migration. You have to remove it manually. Otherwise you will continue to incur charges(if any) for the shared database.

Instructions

• Add the dedicated database to your application:

  $ heroku addons:add heroku-postgresql:ronin
  -----> Adding heroku-postgresql to sushi... done, v69 ($200/mo)
         Attached as HEROKU_POSTGRESQL_RED
  -----> The database should be available in 5-15 minutes
         Use `heroku pg:wait` to track status
  

• Track the progress of the database creation:

  $ heroku pg:wait 
  Waiting for database HEROKU_POSTGRESQL_RED... done       
  

• Get the connection credentials of the newly created database

  $ heroku pg:info
  
  === HEROKU_POSTGRESQL_BLACK
  Plan         Ronin
  Status       available
  Data Size    5.1 MB
  Tables       0
  PG Version   9.0.5
  Created      2011-10-10 17:59 UTC
  Conn Info    "host=ec2-107-22-255-345.compute-1.amazonaws.com 
               port=5432 dbname=dk2sf5va7dsalklkdsj3rd 
               user=uy5gymvzvyast6ee sslmode=require 
               password=pssajjhjhfa2yzx1q8g48dp1mo3a"
  

• VS1: Verification step 1: Note down the count of users in the current database

  $ heroku console
  >> User.count
  => 1024
  >> exit
  

• Enable the mainenance mode. This will prevent any further changes to the shared database.

  $ heroku maintenance:on 
  

• Create a backup of the shared database. Note down the backup id.

  $ heroku pgbackups:capture --expire 
  
  SHARED_DATABASE (DATABASE_URL)  ----backup--->  b136
  ?[0KCapturing... doneB -
  ?[0KStoring... done
  

• VS2: Verification step 2: Check the count of users in the dedicated database. The database will throw an error in this step.

  $ psql "host=ec2-107-22-255-345.compute-1.amazonaws.com port=5432 dbname=dk2sf5va7dsalklkdsj3rd user=uy5gymvzvyast6ee sslmode=require password=pssajjhjhfa2yzx1q8g48dp1mo3a"
  => select count(*) from users; 
  ERROR:  relation "users" does not exist
  LINE 1: select count(*) from users;  
  => \q
  

• Seed the dedicated database from the the backup

  $ heroku pgbackups:restore HEROKU_POSTGRESQL_RED b136 --confirm
  
  ?[0KRetrieving... donet |
  ?[0KRestoring... doneB \-
  

• VS3: Verification step 3: Count of users in the dedicated database should match the count returned in the step VS1

  $ psql "host=ec2-107-22-255-345.compute-1.amazonaws.com port=5432 dbname=dk2sf5va7dsalklkdsj3rd user=uy5gymvzvyast6ee sslmode=require password=pssajjhjhfa2yzx1q8g48dp1mo3a"
  => select count(*) from users; 
   count
  -------
    1024
  (1 row)
  => \q
  

• Make the dedicated database as the primary database for your application

  heroku pg:promote HEROKU_POSTGRESQL_RED
  

• VS4: Verification step 4: Count of users in the heroku console should match the count returned in step VS1

  $ heroku console 
  >> User.count
  => 1024
  >> exit
  

• Activate the application

  heroku maintenance:off --account thinkspeed
  

• Deactivate the paid shared database plan

Deploying to Heroku

App made, now it’s time to deploy. It’s easy once both git and heroku as well as a new app (via `heroku create`) are setup on the system. CD to the app directory and do in order:

git add .

git commit -m "message goes here"

git push heroku master

Then it’s time to prepare the database so I run:

heroku run rake db:migrate

This actually gives me a strange error:

rake aborted!
bad URI(is not URI?):

However, running `heroku logs` reveals:

/Users/grinch/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/net/http.rb:644:in `initialize': getaddrinfo: nodename nor servname provided, or not known (SocketError)

Well, that’s pretty obvious, I haven’t added the Redistogo add-on in this application’s deployment. Let’s do that quick with:

heroku addons:add redistogo:nano

Done! Let’s test it up by firing up `heroku run console` and popping in:

REDIS.set("answer", 42)

It responds with “ok” - we’re in business. When trying to migrate the database again, it works great. I try accessing the app’s URL and it’s live!