Hello Steve, You are right, Ignite requires all fields participating in affinity calculation to be included in the key. The main reason behind this restriction is that Ignite is a distributed system and it is an absolute requirement to be able to calculate affinity based only on a key.
Imagine the following situation: you have 100 nodes in a cluster and run a cache.get(key). If affinity key were not included in the object key, Ignite would have to broadcast the request to all nodes in the cluster because the affinity node cannot be computed. This approach does not scale. I cannot recall any other approaches other than adding the surrogate key to the object key. In other words, when affinity is used, you either need to know in advance the full key (object key + affinity key), or use Ignite SQL fields query, but this will broadcast the request to all nodes in the cluster. Hope this helps, AG 2016-12-09 12:55 GMT+03:00 steve.hostettler <steve.hostett...@gmail.com>: > Hello, > > first let me apologize if there is any double submit. I think that my first > post on this subject was not visible because I did not do the subscription > completely. > > > My understanding is that affinities can only be based on fields in the key. > Is this correct? This seems counter-intuitive since most of the time, the > affinity will be based on some sort of central entity and therefore on a > foreign key to that table (surrogate key). > > That would mean that if I have a primary key with surrogate key I would > have > to add the central table surrogate key to object key (which will break 3rd > normal form). The other alternatives is to retrieve the object from the > cache in the affinity function but at that time I do not whether the other > cache has been already loaded. Furthermore, this would hit the performances > dramatically. > > Any advice? > > Many thanks in advance > > > > -- > View this message in context: http://apache-ignite-users. > 70518.x6.nabble.com/Affinity-based-on-the-fields-NOT-in- > the-key-tp9457.html > Sent from the Apache Ignite Users mailing list archive at Nabble.com. >
