# Database migration

[Detailed information about this](http://ian-shafer.github.io/2016/02/02/db-migrations/)

## Setup

#### Configuration
All configuration needed is done in .configuration.sh.
Note that a
[.pgpass](http://www.postgresql.org/docs/9.3/static/libpq-pgpass.html) file will
do most of the times as well and therefore configuration is not mandatory.

#### Migration files
The files in the /migrations directory are changes to the scheme, not the full
scheme.

The naming convention for migration files are:
- 000.000
- 000.001
- 000.002
- 000.003
- 000.004
- ...and so on

**Example**
The first file, `migration/000.000` may look like this:
```
create table users (
  name varchar(32) not null,
  primary key (name)
);
```

The second file, `migration/000.001` may look like this:
```
alter table users
add email varchar(256) not null;
```

#### Prerequisites
One table needs to be created for the database to make this work:

```
CREATE TABLE database_versions (
  version varchar(32) not null,
  is_active boolean not null default false,
  creation_date timestamp not null default current_timestamp
);
```

To do the actual migration, then just run:
```
# ./db-upgrade
```