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# Erlang PostgreSQL migrations utils
----------------------------------------------------

## Description ##

Project is based on epgpool and epgsql.
It supports `sql` and `erl` migrations description.

## Usage ##

1. Create migrations folder (for example, `./migrations`)  
2. Create migration file with numeric prefix and `.erl` or `.sql` extension.  
The prefix must be unique monotonically increasing integer (1,2,3...).  
No dupplicates allowed!  
  * In case of `erl` you need to implement `dbschema_migration` behaviour.  
  * In case of `sql` you need to write your sql commands directly.  
    And specify `-- up` and `-- down` comments to separate "up" migration part from "down"
3. Run `dbschema:up(MigrationDir)` in you `_app.erl` start function.
4. To downgrade call `dbscheam:down(MigrationDir, PrefixNum)`

## Sql migration example

./migrations/1-init.sql

```sql
-- Up

create table test(
    id serial primary key,
    name text
);

-- Down

drop table test;
```