wal2json VS mria

To illustrate the above, let’s look at an example, using wal2json for convenience. An update event looks something like this:

You could also use tools in conjunction with logical replication to stream changes, like debezium or wal2json.

I've done CDC before for mysql and postgres, in both cases, rolled my own 200~ loc python scripts. No experience with DMS. Debezium, as I understand, needs a kafka topic to stream to, so wasn't workable for us. Rolling our own proved to be fairly trivial. For postgres, there's wal2json https://github.com/eulerto/wal2json

I was researching for the whole day and found out https://github.com/eulerto/wal2json and postgres bult-in `pgoutput` plugin help me to catch the changes.

I don't think this is something for "rails" to do per se, and more the underlying DB. replication tools to capture a "change log". I have use postgres Write Ahead Logs (WAL) shipped to s3 in json format https://github.com/eulerto/wal2json

[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

wal2json Output Plugin that converts WAL output to JSON objects [Open Source] pg_recvlogical Postgres app that can consume update stream [Out-of-the-box with Postgres] decoderbufs Output Plugin that delivers data as protobuf [Open Source, Used in Debezium]

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.