---
last_updated: 2019-06-18
---
# Migrating from MySQL to PostgreSQL
This guide documents how to take a working GitLab instance that uses MySQL and
migrate it to a PostgreSQL database.
## Requirements
NOTE: **Note:**
Support for MySQL was removed in GitLab 12.1. This procedure should be performed
**before** installing GitLab 12.1.
[pgloader](https://pgloader.io/) 3.4.1+ is required.
You can install it directly from your distribution, for example in
Debian/Ubuntu:
1. Search for the version:
```bash
apt-cache madison pgloader
```
1. If the version is 3.4.1+, install it with:
```bash
sudo apt-get install pgloader
```
If your distribution's 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
```
For other distributions, follow the instructions in PostgreSQL's
[download page](https://www.postgresql.org/download/) to add their repository
and then install `pgloader`.
If you are migrating to a Docker based installation, you will need to install
pgloader within the container as it is not included in the container image.
1. Start a shell session in the context of the running container:
``` bash
docker exec -it gitlab bash
```
1. Install pgloader:
``` bash
apt-get update
apt-get -y install pgloader
```
## Omnibus GitLab installations
For [Omnibus GitLab packages](https://about.gitlab.com/install/), you'll first
need to enable the bundled PostgreSQL:
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](../administration/restart_gitlab.md#omnibus-gitlab-reconfigure)
for the changes to take effect.
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.
Next, we'll use `pgloader` to migrate the data from the old MySQL database to the
new PostgreSQL one:
1. Save the following snippet in a `commands.load` file, and edit with your
MySQL 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
```
You can now verify that everything works as expected by visiting GitLab.
## Source installations
For installations from source that use MySQL, you'll first need to
[install PostgreSQL and create a database](../install/installation.md#6-database).
After the database is created, go on with the following steps:
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. Install Gems related to Postgresql
```bash
sudo -u git -H rm .bundle/config
sudo -u git -H bundle install --deployment --without development test mysql aws kerberos
```
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.
Next, we'll use `pgloader` to migrate the data from the old MySQL database to the
new PostgreSQL one:
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
```
You can now verify that everything works as expected by visiting GitLab.
## Troubleshooting
Sometimes, you might encounter some errors during or after the migration.
### Database error permission denied
The PostgreSQL user that you use for the migration 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
#<THREAD "lparallel" RUNNING {10078A3513}>:
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
# Omnibus GitLab
sudo gitlab-rake cache:clear
# Installations from source
sudo -u git -H bundle exec rake cache:clear RAILS_ENV=production
```