walrus VS mria

Wen Bo from the Supabase Realtime team here!

We actually use https://github.com/supabase/walrus to get the database changes and we're planning on moving to a Rust worker (https://github.com/supabase/walrus/tree/worker/worker) for better performance especially in the RLS-enabled use case.

I promised José that I would check out Postgrex.ReplicationConnection and we might add it in to our Supabase Realtime some time in the future.

[0] https://supabase.com [1] https://github.com/supabase/realtime [2] https://github.com/eulerto/wal2json [3] https://github.com/supabase/walrus [4] https://gsd.di.uminho.pt/members/cbm/ps/delta-crdt-draft16ma... [5] https://supabase.com/blog/2022/04/01/supabase-realtime-with-... [6] https://fly.io [7] https://github.com/supabase/realtime/tree/multiplayer [8] https://github.com/supabase/supabase/tree/master/docker

[Supabase cofounder] thanks for the kind words.

We're about to wrap up Row Level Security on our real-time APIs too[0] - soon you'll be able to use Policies universally on all APIs.

[0] https://github.com/supabase/walrus

We are adding this to the database now: https://github.com/supabase/walrus

Mria is an open source extension to Mnesia that adds eventual consistency to clusters. Most of the features described earlier still apply to it, the difference is how data is replicated between nodes. Mria switched from a full mesh topology to a mesh+star topology. Each node assumes one of two roles: core node or replicant node.

In EMQX 5.0, we attempted to mitigate this issue in a new DB backend type called RLOG (as in replication log), which is implemented in Mria. Mria is an extension to the Mnesia database that helps it scale horizontally by defining two types of nodes: i) core nodes, which behave as usual Mnesia nodes and participate in write transactions; ii) replicant nodes, which do not take part in transactions and delegate those to core nodes, while keeping a read-only replica of the data locally. This helps to reduce the risk of split-brain scenarios and lessens the coordination needed for transactions, since fewer nodes participate in it, while keeping read-only data access fast, since data is available locally for reading in all nodes.

Mria is an open-source extension to Mnesia that adds eventual consistency to the cluster.

> write-up soon as a guide for Python developers moving to Elixir

Awesome initiative!

> ETS as a KV/document store to hold user and application state and then reacting to changes in to that the way you are here

This is actually pretty interesting. I can't speak to ETS but Mnesia has replication and you can expose the replication log using something like https://github.com/emqx/mria. I've only had a cursory look at this so I could be wrong about its capabilities but it would be an awesome extension to the new Realtime if possible.