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Comment by shane_b | Hacker News Reader

I use couch and pouch frequently. For replication mostly.

I’ve copied airtable data to it in the past.

Recently I implemented an event store CQRS system designed to be usable offline. I considered syncing events to the client via sockets but I needed to implement diffs. So I use couch and pouch as read only side of CQRS with an append only event CouchDB. The actual data is in Postgres.

Authorization is tricky. I do not recommend trying to do document level access control. I simply added an express endpoint that allows only reads and checks the session user for which table they can access. Then pass the request to couch.

Overall works really well. I recently turned off live sync for web and react native and loop over all of my databases on a set timeout interval. I had trouble with many connections at once.

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> Authorization is tricky. I do not recommend trying to do document level access control.

If you're trying to do that, true. But if you simply let the user sync his data as he pleases, auth is quite easy with the library I maintain (link in my profile).

> I had trouble with many connections at once.

Can you elaborate on how many? And Did you increase max_db_open and the necessary OS limits? I'm currently planning to go the other way, but also a bit worried that too many open connections can cause trouble.

Neat project. If the data belongs to only that user it works pretty well. I run into trouble with sharing across users on a team and individual user sharing. In that case, I see most solutions use express as middleware for the couchdb connection.

> Can you elaborate on how many?

For web, I can have as many as I want syncing. I haven’t stress tested it yet tho. I have a CouchDB in prod that throws an error message about connection limit a few times a day. This one writes and reads. It restarts the docker container to recover since I haven’t had time to investigate. You may have given me the answer :)

On React Native, I’ve had odd behavior around 5 connections. That’s where I need to periodically poll for syncing. It works out best since the user is offline most of the time and downloads infrequently.

> I run into trouble with sharing across users on a team and individual user sharing. In that case, I see most solutions use express as middleware for the couchdb connection.

A shared databases where everyone can read but only some can write is very much possible with design docs. And when being flexible with assigning/revoking roles + creating/replicating data, a lot can be modelled without a proxy.

But yeah, at some point it's probably easier to use a proxy than to do weird stuff with databases and roles.

When i used it for web I hit a max of 6 simultaneous connections in chrome. I seem to recall that it was an (intended) browser limitation - but it doesn't throw any errors, so it's not very obvious. I forked the socket-pouch library and changed it a bit to sync unlimited db's over a single websocket connection. It worked like a charm (despite my messy code).

If you're hitting the same issues, this might be it. A non-throwing limitation in the browser runtime.

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