[feat][pip] PIP-454: Metadata Store Migration Framework

[merlimat]

Motivation

Modifications

Verifying this change

• Make sure that the change passes the CI checks.

(Please pick either of the following options)

This change is a trivial rework / code cleanup without any test coverage.

(or)

This change is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(example:)

• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository:

[lhotari]

LGTM, just a few comments / questions.

[eolivelli]

A couple of questions:

1. is it possible to also migrate back from Oxia to ZooKeeper ?
2. this PIP is not about the metadata store to coordinate geo replication, should we state it explicitly ?

[merlimat]

Good questions.

1. is it possible to also migrate back from Oxia to ZooKeeper ?

While the mechanism can be quite generic, the tricky part to make it work seamlessly is to carry over the same version ids on each metadata record. That allows brokers and bookies conditional writes to not fail in the migration.

In Oxia we were able to add explicit override for this specific purpose. With ZK it's unfortunately not as easy.

2. this PIP is not about the metadata store to coordinate geo replication, should we state it explicitly ?

Good point. I'll highlight this more.