How to avoid DROP DEFAULT statements with Doctrine 2 Migrations diff on first run? - postgresql

Question

I had an existing PostgreSQL database with a table created like this:
CREATE TABLE product (id SERIAL PRIMARY KEY, name VARCHAR(100) DEFAULT NULL)
This table is described in a YML Doctrine2 file within a Symfony2 project:
Acme\DemoBundle\Entity\Product:
type: entity
table: product
fields:
id:
id: true
type: integer
nullable: false
generator:
strategy: SEQUENCE
name:
type: string
length: 100
nullable: true
When I run for the first time the Doctrine Migrations diff task, I should get a versioning file with no data in the up and down methods. But what I get instead is this :
// ...
class Version20120807125808 extends AbstractMigration
{
public function up(Schema $schema)
{
// this up() migration is autogenerated, please modify it to your needs
$this->abortIf($this->connection->getDatabasePlatform()->getName() != "postgresql");
$this->addSql("ALTER TABLE product ALTER id DROP DEFAULT");
}
public function down(Schema $schema)
{
// this down() migration is autogenerated, please modify it to your needs
$this->abortIf($this->connection->getDatabasePlatform()->getName() != "postgresql");
$this->addSql("CREATE SEQUENCE product_id_seq");
$this->addSql("SELECT setval('product_id_seq', (SELECT MAX(id) FROM product))");
$this->addSql("ALTER TABLE product ALTER id SET DEFAULT nextval('product_id_seq')");
}
}
Why are differences detected? How can I avoid this? I tried several sequence strategies with no success.

Answer 1

A little update on this question.
Using Doctrine 2.4, the solution is to use the IDENTITY generator strategy :
Acme\DemoBundle\Entity\Product:
type: entity
table: product
id:
type: integer
generator:
strategy: IDENTITY
fields:
name:
type: string
length: 100
nullable: true
To avoid DROP DEFAULT on fields that have a default value in the database, the default option on the field is the way to go. Of course this can be done with lifecycle callbacks, but it's necessary to keep the default value in the database if this database is used by other apps.
For a "DEFAULT NOW()" like default value, the solution is the following one:
Acme\DemoBundle\Entity\Product:
type: entity
table: product
id:
type: integer
generator:
strategy: IDENTITY
fields:
creation_date:
type: datetime
nullable: false
options:
default: CURRENT_TIMESTAMP

Answer 2

Doctrine 2.0 does not support the SQL DEFAULT keyword, and will always try to drop a postgres default value.
I have found no solution to this problem, I just let doctrine handle the sequences itself.

Answer 3

This is a opened bug registered here :
http://www.doctrine-project.org/jira/browse/DBAL-903