junixsocket VS Flyway

I've recently looked again into the strange world of IBM operating systems (z/OS, IBM i, AIX), primarily because they all run Java, and my open source library junixsocket (https://github.com/kohlschutter/junixsocket) needed a corresponding JNI (C code) implementation on these platforms for the native part of supporting UNIX domain sockets in Java. Of these IBM OSes, I found that z/Os was the weirdest one.

Since you're an enterprise consultant already, you probably already know that there's always an opportunity to cut down expenses/technical debt, while providing justification for past decisions made by the company (after all, they've probably invested quite a lot in that infrastructure, so these decisions couldn't have been wrong...)

Depending on how deep down the rabbit hole you dare to go, there may be a pot of gold waiting for you or a black hole that sucks the livelihood out of your body. After all, it's mostly a legacy system. Don't expect entirely new systems being written for those niche operating systems. But maybe you find your very own niche in there.

I know a company that I worked with in the past has their main business powered by IBM mainframes, and they may well keep that system going for the foreseeable future. A lot of code may already be running on zSystems Linux or be converted to run on it. At that point, you largely only have a different processor architecture to deal with, and some minor, yet annoying incompatibilities and restrictions that you will encounter soon enough.

A good starting point to learn about IBM z may be "IBM Z Xplore" (https://ibmzxplore.influitive.com/), which gives, apart from an online tutorial with challenges, some free access to IBM z systems. Also check out IBM ZD&T for Learners Edition (https://ibm.github.io/zdt-learners-edition-about/).

Don't expect that IBM responds to any of your inquiries unless you already are a paying customer.

The session logs show that the application loads configurations and establishes a connection with a PostgreSQL database. This involves initializing a HikariCP connection pool and Flyway for database migrations. The logs confirm that the database schema validation and migration checks were successful. The startup of the Jetty HTTP server follows, and the server becomes operational and ready to accept requests on the specified port.

Also RedGate, but Flyway has some reasons to recommend it over RedGate Deploy depending on your DBAs/workflows: https://flywaydb.org/

(Though I don't think it is "complete" or "perfect", either.)

EF Migrations are in a really good place now if you like/don't mind C# as a language (and you can easily embed SQL inside the C#, too, but there are benefits to being able to also run high level C# code). With today's tooling you can package your migration "runner application" as a single deployable executable for most platforms. You can build the executable once and run it in all your environments. (The same tool that updates your QA and Staging updates your Prod, testably running the same migrations.) Given the single executable deployable I might even consider using it for projects not themselves written in C#.

There is a bit of tooling needed but is already around. For Java for example I had very good experience with a combination of flyway [1] for migrations, testcontainers [2] for making integration tests as easy as unit tests and querydsl [3] for a query and mapping layer.

[1] https://github.com/flyway/flyway

[2] https://java.testcontainers.org/modules/databases/postgres/

[3] https://github.com/querydsl/querydsl

When software starts using a database, it's advisable to have version control, just as we have Github to control our source code. This is all to be sure about what was executed for that specific version. For Java and Spring boot, we have the Flyway framework that aims to resolve this situation, free of charge.

If you're looking for tools, like https://www.liquibase.com/ or https://flywaydb.org/, which are database-state-based schema migration toolkits - it might be relatively straightforward to build similar ones using Databricks SQL drivers.

Honestly I kind of wish there was a Lukas Eder database migration library. Call it whatever jooq-migration. At least I would have more insight of what is going on (<-- seriously look at the commit history).

This is a 4th option, which should play nice with ArgoCD. The following example runs flyway as a k8s job. The desired migration changes are recorded as files within the chart. This helm chart can be integrated with your application (Using hooks to determine when the migration job is run) or run manually.

By using an opinionated framework within the app/service (like Flyway, Migrate, Diesel, etc). Schema migrations happen on app/service start-up.

Depending on the language or platform there are libraries you can use to manage this, such as Prisma on node and Flyway for Java/JVM.

It's probably overkill but I've used github plus flyway at a couple places in the past which is pretty nice tool for tracking changes to a variety of db's, it's also very helpful if you ever need to replicate a db in a new region/environment.