Migrations and feature branches

[Florian Ebeling]

Is there a common practice how to apply migrations for staging systems running various feature branches?

Assume there is a db of significant size, and feature branches including migrations are pushed to this server instance.

Just calling `rake db:migrate` won't be enough, as often it will be the situation that a feature branch introduced a schema change, and the subsequently deployed branch doesn't work with it. So at deployment, I'd need to roll back one or more migration steps. 

I know this can be done by invoking `db:migrate VERSION=v`. 

But how would you establish what to pass as `v` here from the new branch?

(Or is loading a nightly db dump and uniformly migrate upwards still the best idea?)

Florian

[Walter Lee Davis]

The we we manage this is to have a separate staging database, cloned monthly from the production database (to get a useful sample of data to play with) and then run migrations up and down in that database as we check things out for review. Does that help?

Walter

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> Florian
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[Walter Lee Davis]

> On Sep 18, 2018, at 6:19 AM, Florian Ebeling <florian...@gmail.com> wrote:
>

> But how would you establish what to pass as `v` here from the new branch?
>

If you have run a migration up in staging, you can get its version from rake db:migrate:status (but I'm pretty sure you knew that). Are you talking about having run migrations from various branches up in staging all at various times? Does staging work as a sort of "integration branch" combining features from multiple stories?

Walter

[Hassan Schroeder]

On Tue, Sep 18, 2018 at 3:19 AM, Florian Ebeling
<florian...@gmail.com> wrote:
> Is there a common practice how to apply migrations for staging systems
> running various feature branches?
>
> Assume there is a db of significant size, and feature branches including
> migrations are pushed to this server instance.

Can you have a staging system per feature branch? If you're working
in the cloud it's not a huge deal to set that up, and once you have the
infra code written (chef, terraform, etc.), you can have those systems
only run while they're being used.

Alternatives:
1) multiple dockerized db instances per staging server
2) discrete db schema per feature branch on one big DB server
3) have staging deployments do an initial refresh from a base image

Very much an "it depends" question :-)

FWIW,
--
Hassan Schroeder ------------------------ hassan.s...@gmail.com
twitter: @hassan
Consulting Availability : Silicon Valley or remote