Ask HN: Zero-downtime migration from MongoBD to PostgresSQL

1 pointsfosron3y ago3 comments

Hey,

we are looking for an efficient way to migrate away from MongoDB to Postgres. Were hosted on Mongo Cloud ATM but i dont think theyll provide us a solution.

Key thing is were running a system which can not go down, and looking online i could not find anything that seems reliable and would help us to achieve that. Developing an in house solution for a one-off job also seems to be not the best one.

Maybe someone has experience regarding that, and could at least point in a good way? Would be really helpful. Thanks!

3 comments

gtirloni3y ago

I'm afraid there is no quick solution. Your app will have to write to both temporarily and make the switch, no way around adding logic to it.

Even if a multi-DB polyglot proxy/gateway exists, you'd still have to specify the relations, constraints, etc... at which point you'd better do that in your app to avoid lock-in.

Google for "mongodb to postgres downtime". I've found a few detailed articles.

fosronOP3y ago

Yeah, thats what i think too, thanks. Hoping for a miracle solution. And also i did google, and i understand that the schema will have to be provided, we can do that, but the actual data transfer is the pain point here. I tried one solution, Airbyte, locally, but its mongo support is in beta, and does not use a feature like WAL, etc.

surprisetalk3y ago

I can think of a few different solutions for you, depending on your write/read loads and DB size. Unfortunately, I don't think any of your solutions will be quick/easy.

Feel free to schedule a call with me! I've done 3 large NoSQL to PG migrations for different orgs.

[1] https://calendly.com/taylor-town/30min

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