Prisma

What’s the recommended guidance for migrating a production database without downtime?

Migrating from one provider to another provider? Or migrating its structure from one schema to another (rename a table for example)?

<@UMVHHLEE8> I'm interested in this as well

In our case we're planning to remain on the same provider(aws)

We did the database fixes, from prisma 1 to prisma 2. and currently in the process of migrating the application layer

<@UUX8A0N5C> I’m curious about your exact usecase with more info, would you be ok creating a new discussion here maybe?
<https://github.com/prisma/prisma/discussions/>

Conversation will continue there <https://github.com/prisma/prisma/discussions/5955>

<@UMVHHLEE8> Sorry I didn’t get back to you yesterday, my use case is deploying schema migrations.

So if the change is an addition it’s nice and easy, “just deploy”

If you have changes that break things I can recommend looking into the expand and contract pattern <https://www.tim-wellhausen.de/papers/ExpandAndContract/ExpandAndContract.html>

We’re planning to add some docs on some common scenarios <https://github.com/prisma/docs/issues/1351>

Is that relevant to what you want to achieve <@U01GFDA05L5>?

If you could, please also include docs specific to load balanced environments (eg, where different servers may have differing versions of the code)

Though that may be substantially similar to zero-downtime deployments

Yes it is <@UMVHHLEE8>, thank you! Yes, <@U8SF1JN7Q> we have a load balanced environment as well. And to his point, if its an addition, then there won’t be an issue. I was also reading this article which had a similar perspective: <https://betterprogramming.pub/evolving-a-database-schema-10b7f4094d14>

I liked his pattern of deploying through CI on an empty table and testing against the previous version of the code to help ensure there are no breaking changes.

<@U01GFDA05L5> now that you mention deploying to an empty table, I found this open source tool made by Github. Supposedly it's better than Facebook's and Percona tools: <https://github.com/github/gh-ost>

I'm not sure if this would help us. What do you think <@UMVHHLEE8> ?

Well now I’m sad that this is MySQL and not Postgres like we’re using haha

Although it has limitations, like it does not support foreign keys and triggers for example, but these weren't supported since the release in 2016. So either not updated docs or they're really unsupported:
<https://github.com/github/gh-ost/blob/master/doc/requirements-and-limitations.md>