IBM DB2 + Doctrine - Auto increment in composite primary keys - laravel

Question

My problem is easy to understand and many mentioned here in Stackoverflow with references to Doctrine docs.
Every entity with a composite key cannot use an id generator other
than "ASSIGNED". That means the ID fields have to have their values
assigned before you call EntityManager#persist($entity).
I tried this, getting last generated ID, adding + 1 to its value and persisting entity. The problem is that a third party software that uses the same IBM DB2 database, cannot add a row, because the auto increment index is not updated when I insert a row in that way.
Is there a way to make this work or a way to update the table auto increment index?
Thanks in advance.
EDIT
In order to help you to better understand what I want/have to achieve, I will show you my example.
EntityClass
class Entity
{
/**
* #ORM\Id
* #ORM\Column(type="string", name="serie")
*/
protected $serie;
/**
* #ORM\Id
* #ORM\Column(type="integer", name="reference")
* #ORM\GeneratedValue
*/
protected $reference;
// More code...
}
Multiple primary keys are allowed by doctrine, but for some reason, when I fill the entity this way
$entity = new Entity();
$entity->set("serie", date('Y')); // Custom setter that search the property and sets the value. In this case, current year as string
// More assignements, except for the autoincrement value
$em->persist($entity);
$em->flush();
It throws an exception saying that one of the ids is not filled and MUST be filled in a composite key entity, but it is an auto increment column and I need to make it work that way, find a way to get the next auto increment value for the table or update auto increment value for the table in IBM DB2. If not, the other third party software will crash if I get the max value of the auto increment column, increase that value by one and assign it to the entity manually.
The query:
SELECT presence FROM DB2ADMIN.PRESENCES WHERE serie LIKE 2017 ORDER BY presence DESC FETCH FIRST 1 ROWS ONLY;
If you need any further information, let me know.

Answer 1

There's two ways to do this, but since you don't have access to transactions (and apparently don't care about gaps), I don't recommend one of them.
The first way, which I'm recommending you not use, is to create a table to hold the generated value, incrementing that, and returning it. I previously answered a question about this for SQL Server, but the concept should translate. Note that some of the utility is lost since you can't generate the value in a trigger, but should still work. The primary remaining issue is that the table represents a bottleneck, which you're not getting much benefit out of.
The second way is just to use a separate SEQUENCE for each year. This is somewhat problematic in that you'd need to create the object each year, but would be much faster to get a number. You'd also be essentially guaranteed to have gaps.
Note that I'm always a little suspicious of primary keys where the value is incremented and has value, especially if gaps are allowed.