---
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
#<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
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
```