I searched across many threads and issues but I doesn't found the answer.
When I use the Realm Objects Server and the clients connects to the server, the whole DB is synced across all the clients?
In other words, if I have a public DB with millions of objects, relations, etc all the clients have a copy of the whole DB on their devices?
I'll need Realm sync feature but I don't know how to sync occurs. Is the sync incremental? Every user has the objects that device needs to make queries?
My app will increment the size every hour, and the sync feature of the Realm is perfect for me, but I have doubts about the size of DB over the time and how clients sync a lot of data.
Thanks in advance!
At present, yes. Public Realms are synchronized in their entirety to every client's device. The entire list will initially be downloaded when the client's device connects for the first time, and from that point on, any additional changes will be synchronized at the time they are made on the server.
That being said, all Realm files are compacted (ie, all empty allocated space is removed and all strings are condensed), and then compressed with gzip before being downloaded to the client, so as long as the public Realm doesn't contain large binary blobs, even very large files should come down quite quickly.
It's on the roadmap to add partial replication to the Realm Mobile Platform. This will allow only portions of a single Realm file to be synchronized to specific clients. However there are no concrete plans for when this will be released.
For the time being, the easiest thing to do would be to maintain the master list of data on the server, and copy only the desired data to each user's private Realm. However since this would require custom logic to be executed on the server, it would require the Professional or Enterprise editions of the Realm Mobile Platform.