Ways around schema migration deficiencies

[gedw99]

Had an idea .

schema migration does not work with marmot .

so one solution is to detect that a Migration is happening, tell all nats nodes to delete all relevant state and block connections ( maybe needed ) , so migration then happens on the leader SQL DB and is then given to all others nodes, then startup again into master / master…

it’s basically a stop the world for a second approach to get us a way out for now .

What are the issues with it ?

Can we detected it off the WAL though ? no, the WAL is after the fact so its too late by then ? In which case we need the App to formally tell us use before hand, that it wants to do a migration and to give us the migration DDL. SO then we can tell the other nodes too in this dance.
And we may need to tell other app instances when it's all back to normal. https://github.com/RussellLuo/hats) which is a web hook system running with NATS can do this for us.

Main thing to keep in mind is that its not perfect but gets us something that does not need intervention.

I would like to move this forward so seeking feedback.

@maxpert ?

@WesselAtWork

[gedw99]

https://github.com/automerge/automerge-go also works for me.

Its CRDT that works at golang and was level ( in browser ).

basic todo demo works for me well.