On 22 April 2016 at 19:42, 'francesco' via doctrine-user <
[email protected]> wrote:
> Hi there,
>
> struggling trying to understand how the PESSIMISTIC_LOCK is working.
>
> I have this code:
>
> $this->getEntityManager()->getConnection()->beginTransaction();
>
> $queryBuilder = $this->getEntityManager()->createQueryBuilder();
> $query = $queryBuilder
> ->select('foo')
> ->from(Foo::class, 'foo')
> ->where('foo.id = :fooId')
> ->setParameter('fooId', $fooId)
> ->getQuery();
>
> $query->setLockMode(LockMode::PESSIMISTIC_WRITE);
>
>
> inside my repository.
>
> If I try to do to update that row that I'm selecting with the lock during
> the transaction (so before the commit of the transaction), the lock works
> properly.
>
That seems about right to me. In general:
1. start transaction
2. do something with a pessimistic lock (find)
3. interact with the data (multiple reads allowed too)
4. commit
> But if a try to SELECT the same row during the transaction, I'm not having
> any problem at retrieving data. I was expecting the same behaviour for read
> and write because of the doctrine documentation (here
> <http://doctrine-orm.readthedocs.org/projects/doctrine-orm/en/latest/reference/transactions-and-concurrency.html#pessimistic-locking>
> ):
>
> Pessimistic Write (Doctrine\DBAL\LockMode::PESSIMISTIC_WRITE), locks the
> underlying database rows for concurrent *Read and Write* Operations.
>
That seems correct: the DB-level transaction should be the owner of the
lock, so you can re-fetch the data as many times as you want. Once the
transaction is complete, other transactions should be able to access the
previously records.
Marco Pivetta
http://twitter.com/Ocramius
http://ocramius.github.com/
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