[infinispan-dev] conflicts resolution in DeltaAware

[Sanne Grinovero]

2011/4/11 Mircea Markus <mircea.markus at jboss.com>:
>
> On 8 Apr 2011, at 18:30, Emmanuel Bernard wrote:
>
> Yes I think that would fit the bill. Let me give some more background
> Background
> In Hibernate OGM, we store collections in a single key essentially as a
> Set<Map<String,Object>> ie as a set of tuples, esch tuple representing the
> equivalent of one row of an association table in a relational database. The
> reason for that is to be able to get the collection state by doing key
> lookups. If we were to store each tuple of the collection in a separate key,
> we would have no way to get the list of matching keys for a given collection
> (unless you get a key with the list of keys for a collection but then you
> are just moving the problem instead of fixing it.
>
> Today, we reach scalability problems very quickly as we end up touching the
> collection key every time one entity is added or removed from it. In a
> relational database, this operation scale quite well as locks are acquired
> on each tuple and not on the whole tupes for a given collection.
>
> What we could do is:
>  - use AtomicMap<UUID,Map<String,Object>> instead of Set<Map<String,Object>>
>  - trick infinispan so that it believes that the atomic lock is held at the
> atomic map key level rather than the atomic map as a whole.
>
> Many operations could be done consecutively:
>  - update k1 in T1 and k2 in T2 in concurrently
>  - add k1 in T1 and remove k2 in T2 concurrently
> etc
> what would still fail is:
>  - modify k1 in T1 and k1 in T2 concurrently
>
> You'd get this by using a Cache<UUID, Map<String, Object>>, together with
> fine grained replication.

Hi Mircea, could you elaborate on that? What is fine grained
replication and how is that going to affect locking?

Sanne