--- last_updated: 2018-02-07 --- # Migrating from MySQL to PostgreSQL > **Note:** This guide assumes you have a working GitLab instance with > MySQL and want to migrate to bundled PostgreSQL database. ## Omnibus installation ### Prerequisites First, we'll need to enable the bundled PostgreSQL database with up-to-date schema. Next, we'll use [pgloader](http://pgloader.io) to migrate the data from the old MySQL database to the new PostgreSQL one. Here's what you'll need to have installed: - pgloader 3.4.1+ - Omnibus GitLab - MySQL ### Enable bundled PostgreSQL database 1. Stop GitLab: ``` bash sudo gitlab-ctl stop ``` 1. Edit `/etc/gitlab/gitlab.rb` to enable bundled PostgreSQL: ``` postgresql['enable'] = true ``` 1. Edit `/etc/gitlab/gitlab.rb` to use the bundled PostgreSQL. Please check all the settings beginning with `db_`, such as `gitlab_rails['db_adapter']` and alike. You could just comment all of them out so that we'll just use the defaults. 1. [Reconfigure GitLab] for the changes to take effect: ``` bash sudo gitlab-ctl reconfigure ``` 1. Start Unicorn and PostgreSQL so that we can prepare the schema: ``` bash sudo gitlab-ctl start unicorn sudo gitlab-ctl start postgresql ``` 1. Run the following commands to prepare the schema: ``` bash sudo gitlab-rake db:create db:migrate ``` 1. Stop Unicorn to prevent other database access from interfering with the loading of data: ``` bash sudo gitlab-ctl stop unicorn ``` After these steps, you'll have a fresh PostgreSQL database with up-to-date schema. ### Migrate data from MySQL to PostgreSQL Now, you can use pgloader to migrate the data from MySQL to PostgreSQL: 1. Save the following snippet in a `commands.load` file, and edit with your database `username`, `password` and `host`: ``` LOAD DATABASE FROM mysql://username:password@host/gitlabhq_production INTO postgresql://gitlab-psql@unix://var/opt/gitlab/postgresql:/gitlabhq_production WITH include no drop, truncate, disable triggers, create no tables, create no indexes, preserve index names, no foreign keys, data only ALTER SCHEMA 'gitlabhq_production' RENAME TO 'public' ; ``` 1. Start the migration: ``` bash sudo -u gitlab-psql pgloader commands.load ``` 1. Once the migration finishes, you should see a summary table that looks like the following: ``` table name read imported errors total time ----------------------------------------------- --------- --------- --------- -------------- fetch meta data 119 119 0 0.388s Truncate 119 119 0 1.134s ----------------------------------------------- --------- --------- --------- -------------- public.abuse_reports 0 0 0 0.490s public.appearances 0 0 0 0.488s . . . public.web_hook_logs 0 0 0 1.080s ----------------------------------------------- --------- --------- --------- -------------- COPY Threads Completion 4 4 0 2.008s Reset Sequences 113 113 0 0.304s Install Comments 0 0 0 0.000s ----------------------------------------------- --------- --------- --------- -------------- Total import time 1894 1894 0 12.497s ``` If there is no output for more than 30 minutes, it's possible pgloader encountered an error. See the [troubleshooting guide](#Troubleshooting) for more details. 1. Start GitLab: ``` bash sudo gitlab-ctl start ``` Now, you can verify that everything worked by visiting GitLab. ### Troubleshooting #### Permissions Note that the PostgreSQL user that you use for the above MUST have **superuser** privileges. Otherwise, you may see a similar message to the following: ``` debugger invoked on a CL-POSTGRES-ERROR:INSUFFICIENT-PRIVILEGE in thread #: Database error 42501: permission denied: "RI_ConstraintTrigger_a_20937" is a system trigger QUERY: ALTER TABLE ci_builds DISABLE TRIGGER ALL; 2017-08-23T00:36:56.782000Z ERROR Database error 42501: permission denied: "RI_ConstraintTrigger_c_20864" is a system trigger QUERY: ALTER TABLE approver_groups DISABLE TRIGGER ALL; ``` #### Experiencing 500 errors after the migration If you experience 500 errors after the migration, try to clear the cache: ``` bash sudo gitlab-rake cache:clear ``` [reconfigure GitLab]: ../administration/restart_gitlab.md#omnibus-gitlab-reconfigure ## Source installation ### Prerequisites #### Install PostgreSQL and create database See [installation guide](../install/installation.md#6-database). #### Install [pgloader](http://pgloader.io) 3.4.1+ Install directly from your distro: ``` bash sudo apt-get install pgloader ``` If this version is too old, use PostgreSQL's repository: ``` bash # add repository sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt/ $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list' # add key sudo apt-get install wget ca-certificates wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add - # install package sudo apt-get update sudo apt-get install pgloader ``` ### Enable bundled PostgreSQL database 1. Stop GitLab: ``` bash sudo service gitlab stop ``` 1. Switch database from MySQL to PostgreSQL ``` bash cd /home/git/gitlab sudo -u git mv config/database.yml config/database.yml.bak sudo -u git cp config/database.yml.postgresql config/database.yml sudo -u git -H chmod o-rwx config/database.yml ``` 1. Run the following commands to prepare the schema: ``` bash sudo -u git -H bundle exec rake db:create db:migrate RAILS_ENV=production ``` After these steps, you'll have a fresh PostgreSQL database with up-to-date schema. ### Migrate data from MySQL to PostgreSQL Now, you can use pgloader to migrate the data from MySQL to PostgreSQL: 1. Save the following snippet in a `commands.load` file, and edit with your MySQL `username`, `password` and `host`: ``` LOAD DATABASE FROM mysql://username:password@host/gitlabhq_production INTO postgresql://postgres@unix://var/run/postgresql:/gitlabhq_production WITH include no drop, truncate, disable triggers, create no tables, create no indexes, preserve index names, no foreign keys, data only ALTER SCHEMA 'gitlabhq_production' RENAME TO 'public' ; ``` 1. Start the migration: ``` bash sudo -u postgres pgloader commands.load ``` 1. Once the migration finishes, you should see a summary table that looks like the following: ``` table name read imported errors total time ----------------------------------------------- --------- --------- --------- -------------- fetch meta data 119 119 0 0.388s Truncate 119 119 0 1.134s ----------------------------------------------- --------- --------- --------- -------------- public.abuse_reports 0 0 0 0.490s public.appearances 0 0 0 0.488s . . . public.web_hook_logs 0 0 0 1.080s ----------------------------------------------- --------- --------- --------- -------------- COPY Threads Completion 4 4 0 2.008s Reset Sequences 113 113 0 0.304s Install Comments 0 0 0 0.000s ----------------------------------------------- --------- --------- --------- -------------- Total import time 1894 1894 0 12.497s ``` If there is no output for more than 30 minutes, it's possible pgloader encountered an error. See the [troubleshooting guide](#Troubleshooting) for more details. 1. Start GitLab: ``` bash sudo service gitlab start ``` Now, you can verify that everything worked by visiting GitLab. ### Troubleshooting #### Experiencing 500 errors after the migration If you experience 500 errors after the migration, try to clear the cache: ``` bash sudo -u git -H bundle exec rake cache:clear RAILS_ENV=production ```