前提

以下の続き。実際の作業のメモ。
Heroku Postgresで「PG::InsufficientPrivilege: ERROR: permission denied for relation」エラー - Qiita https://qiita.com/kure/items/ba96d5b31f5e85cfb511

新DB（Hobby Basic）を新規作成→データコピー→旧DB（Hobby Dev）を削除、な流れ

メモ

現状確認

kure@ubuntu ~/ % heroku pg:info                          
=== DATABASE_URL
Plan:                  Hobby-dev
Status:                Available
Connections:           1/20
PG Version:            10.6
Created:               2018-09-27 00:32 UTC
Data Size:             37.8 MB
Tables:                6
Rows:                  20255/10000 (Write access revoked)
Fork/Follow:           Unsupported
Rollback:              Unsupported
Continuous Protection: Off
Add-on:                postgresql-elliptical-xxxxx

新DB作成

結果「HEROKU_POSTGRESQL_COBALT_URL」が出来た。
色の名前が適当に付くらしい。

kure@ubuntu ~/x % heroku addons:create heroku-postgresql:hobby-basic
Creating heroku-postgresql:hobby-basic on ⬢ x... $9/month
Database has been created and is available
 ! This database is empty. If upgrading, you can transfer
 ! data from another database with pg:copy
Created postgresql-shaped-26200 as HEROKU_POSTGRESQL_COBALT_URL
Use heroku addons:docs heroku-postgresql to view documentation
kure@ubuntu ~/ % heroku pg:info                                    
=== DATABASE_URL
Plan:                  Hobby-dev
Status:                Available
Connections:           1/20
PG Version:            10.6
Created:               2018-09-27 00:32 UTC
Data Size:             37.8 MB
Tables:                6
Rows:                  20251/10000 (Write access revoked)
Fork/Follow:           Unsupported
Rollback:              Unsupported
Continuous Protection: Off
Add-on:                postgresql-elliptical-

=== HEROKU_POSTGRESQL_COBALT_URL
Plan:                  Hobby-basic
Status:                Available
Connections:           0/20
PG Version:            10.6
Created:               2018-12-23 14:39 UTC
Data Size:             7.7 MB
Tables:                0
Rows:                  0/10000000 (In compliance) - refreshing
Fork/Follow:           Unsupported
Rollback:              Unsupported
Continuous Protection: Off
Add-on:                postgresql-shaped-

データコピー

数秒で完了。

kure@ubuntu ~/ % heroku maintenance:on
Enabling maintenance mode for ⬢ xxxx... done
kure@ubuntu ~/ % heroku pg:copy DATABASE_URL HEROKU_POSTGRESQL_COBALT_URL
 ▸    WARNING: Destructive action
 ▸    This command will remove all data from COBALT
 ▸    Data from DATABASE will then be transferred to COBALT
 ▸    To proceed, type xxxxx or re-run this command with --confirm
 ▸    xxxx

> 
Starting copy of DATABASE to COBALT... done
Copying... done

利用するDBを変更

kure@ubuntu ~/ % heroku pg:promote HEROKU_POSTGRESQL_COBALT_URL
Ensuring an alternate alias for existing DATABASE_URL... HEROKU_POSTGRESQL_JADE_URL
Promoting postgresql-shaped-26200 to DATABASE_URL on ⬢ ... done
kure@ubuntu ~/ % heroku pg:info                                          
=== DATABASE_URL, HEROKU_POSTGRESQL_COBALT_URL
Plan:                  Hobby-basic
Status:                Available
Connections:           0/20
PG Version:            10.6
Created:               2018-12-23 14:39 UTC
Data Size:             34.5 MB
Tables:                6
Rows:                  20303/10000000 (In compliance)
Fork/Follow:           Unsupported
Rollback:              Unsupported
Continuous Protection: Off
Add-on:                postgresql-shaped-

=== HEROKU_POSTGRESQL_JADE_URL
Plan:                  Hobby-dev
Status:                Available
Connections:           1/20
PG Version:            10.6
Created:               2018-09-27 00:32 UTC
Data Size:             37.8 MB
Tables:                6
Rows:                  20247/10000 (Write access revoked)
Fork/Follow:           Unsupported
Rollback:              Unsupported
Continuous Protection: Off
Add-on:                postgresql-elliptical-

旧DBを削除

kure@ubuntu ~/x % heroku maintenance:off
Disabling maintenance mode for ⬢ ... done
kure@ubuntu ~/x % heroku addons:destroy HEROKU_POSTGRESQL_JADE_URL
 ▸    WARNING: Destructive Action
 ▸    This command will affect the app 
 ▸    To proceed, type x or re-run this command with --confirm
 ▸    x

> x
Destroying postgresql-elliptical-x on ⬢ ... done
kure@ubuntu ~/x % heroku pg:info                                  
=== DATABASE_URL, HEROKU_POSTGRESQL_COBALT_URL
Plan:                  Hobby-basic
Status:                Available
Connections:           0/20
PG Version:            10.6
Created:               2018-12-23 14:39 UTC
Data Size:             34.6 MB
Tables:                6
Rows:                  20303/10000000 (In compliance)
Fork/Follow:           Unsupported
Rollback:              Unsupported
Continuous Protection: Off
Add-on:                postgresql-shaped-x

参考