Feature Status: Idempotency IDs

[PierreZ]

We heavily rely on Idempotency IDs (automatic-idempotency.html) to handle automatic transaction retries introduced in FDB 7.3.0+ (see this analysis). However, this feature is not listed in feature-status.md.

I found two related issues (#11446 on idempotency ID implementation and #10312 on automatic cleanup) but the overall feature status remains unclear.

The documentation mentions important caveats: it only prevents commit_unknown_result (not transaction_timed_out or cluster_version_changed), and it's not recommended for Multi-version client users. The Multi-version client limitation is particularly concerning as it's commonly used in production environments. Given these limitations, could you clarify:

Is this feature production-ready, and in which FDB versions?
What's the Long Term status?
Are there other issues or PRs related to this feature that I should be aware of?

I'm happy to help with any remaining work if needed, though I'd need some guidance to get started as this would be my first Flow/C++ oriented PR.

[jzhou77]

I believe this is still an experimental feature. @atn34 probably can comment on the work left?

[atn34]

Looking back over my notes, I think there are two issues which aren't filed as issues:

• The test for the automatic idempotency cleaner could fail because an idempotency id was automatically cleaned up, but this was misinterpreted as "cleaned too much"
• A transaction that succeeded through the automatic idempotency codepath would not get a commit version in the client.

There are also the caveats which I believe are already documented around cluster_version_changed and transaction_timed_out, both of which could be fixed but would take significant effort.

[PierreZ]

Thanks @atn34!

Could you create the issues with some context in it? In the mean time, I will setup my dev environment.