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Verified Commit 7fcd386a authored by Achilleas Pipinellis's avatar Achilleas Pipinellis
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Clean up the mysql to postgres guide 

This change refactors the pgloader instructions to have
less headings and be more straightforward.
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---
last_updated: 2018-02-07
last_updated: 2019-03-27
---
 
# 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.
This guide documents how to take a working GitLab instance that uses MySQL and
migrate it to a PostgreSQL database.
 
## Omnibus installation
## Requirements
 
### Prerequisites
[pgloader](http://pgloader.io) 3.4.1+ is required.
 
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.
You can install it directly from your distribution, for example in
Debian/Ubuntu:
 
Here's what you'll need to have installed:
1. Search for the version:
 
- pgloader 3.4.1+
- Omnibus GitLab
- MySQL
```bash
apt-cache madison pgloader
```
 
### Enable bundled PostgreSQL database
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 PostrgreSQL's
[download page](https://www.postgresql.org/download/) to add their repository
and then 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
```bash
sudo gitlab-ctl stop
```
 
@@ -40,39 +67,34 @@ Here's what you'll need to have installed:
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. [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
```bash
sudo gitlab-ctl start unicorn
sudo gitlab-ctl start postgresql
```
 
1. Run the following commands to prepare the schema:
 
``` bash
```bash
sudo gitlab-rake db:create db:migrate
```
 
1. Stop Unicorn to prevent other database access from interfering with the loading of data:
 
``` bash
```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:
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
database `username`, `password` and `host`:
MySQL database `username`, `password` and `host`:
 
```
LOAD DATABASE
@@ -90,7 +112,7 @@ Now, you can use pgloader to migrate the data from MySQL to PostgreSQL:
 
1. Start the migration:
 
``` bash
```bash
sudo -u gitlab-psql pgloader commands.load
```
 
@@ -117,170 +139,140 @@ Now, you can use pgloader to migrate the data from MySQL to PostgreSQL:
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.
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
```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
You can now verify that everything works as expected by visiting GitLab.
 
### Prerequisites
## Source installations
 
#### Install PostgreSQL and create database
For installations from source that use MySQL, you'll first need to
[install PostgreSQL and create a database](../install/installation.md#6-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
After the database is created, go on with the following steps:
 
1. Stop GitLab:
 
``` bash
sudo service gitlab stop
```
```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
```
```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
```
```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
```
```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:
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
```
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
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'
ALTER SCHEMA 'gitlabhq_production' RENAME TO 'public'
 
;
```
;
```
 
1. Start the migration:
 
``` bash
sudo -u postgres pgloader commands.load
```
```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.
```
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
```
```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.
 
Now, you can verify that everything worked by visiting GitLab.
### Database error permission denied
 
### Troubleshooting
The PostgreSQL user that you use for the migration MUST have **superuser** privileges.
Otherwise, you may see a similar message to the following:
 
#### Experiencing 500 errors after the migration
```
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
```bash
# Omnibus GitLab
sudo gitlab-rake cache:clear
# Installations from source
sudo -u git -H bundle exec rake cache:clear RAILS_ENV=production
```
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