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treat filter subscription as a subscription to every store matching the filter #110
Description
setup:
assume a client-server architecture where on SyncMap is used with createFIlter on the offline/remote client and addSyncMap +addSyncMapFilter on the backend
problem:
when creating a filter, client and server exchange a lot of messages to:
- subscribe to a list. that's two messages
- subscribe to every item of the list. that's one or two messages depending on if server subscribes a client, or client subscribes by iteself
that's a lot of pressure on the network and synchronisation for really no reason.
solution:
filter subscription is enough for the server to send actions related to every matching item of the channel
there seems no need to explicitly subscribe client to every matching store separately, or maybe I am missing something?
Activity
ai commentedon Sep 9, 2022
Both client and server need IDs of each subscribed element.
If we can find a way to get find them without an action, it always will be a good idea.
Do you have an idea how to make PR?
ngalaiko commentedon Sep 10, 2022
I haven't looked into it too much, but it seems possible.
on the client side:
on the server side:
ai commentedon Sep 10, 2022
It is impossible because log is an async store (for instance, IndexedDB has only async API).
changeaction will not have all model’s fields. As the result it will be impossible to tell is it part of filter or not.Imagine you have
name: 'a'filter and see{ type: 'users/changed', id: 'X', fields: { age: 50 } }. How you will tell that it is your or not item without a list of subscribed IDs?{ age: 50, name: 'a' }Xageto 50. You do not have information of thenameto find did it matched the selection.Ytorole: 'admin'. How do you knowageandnameofYuser?ngalaiko commentedon Sep 10, 2022
given that I already have a full item in the scope (from the init step), I could simply merge it with it
same applies for the server side.
server does have the info. it keeps an index of elements matching the filter in memory for every connected client. when client B changes user with ID X age to 50, it sends an action to the server. server resends it to client A
when filter is created, all of the matching elements (from the initial function in the addSyncMapFilter) are used to create in-memory index.
either way it would be very fast, since it happens without communicating with other clients or servers on the client
ai commentedon Sep 11, 2022
Only if server already send the initial data.
Dangerous (server could have 1000 of client with 10 subscriptions with 1000 elements each). But we can try.