Mongo 4.4 support

[James Rowe]

I am using reactivemongo 1.0.3 and upgrading my application's mongo version to 4.4, but I have some concerns that in the reactivemongo docs, it does not mention mongo 4.4 compatibility. Reading through the documentation and other postings about Mongo 4.4 I've gathered the following information:

* The documentation states only up to 4.2 support, but it seems this is referring to reactivemongo's high-level DSL. There's no mention if its compatible with 4.4 at a driver level, and in local testing, there was no issues with reactivemongo and a mongo 4.4 cluster.
* Other users have mentioned on this mailing list that they use Mongo 4.4 and it seems like there were no compatibility issues there.
* The official mongo version compatibility docs don't seem to mention any driver level changes, suggesting that there shouldn't be any issues (but I'm not a mongo driver dev, so what do I know?)

Before I push out an update to bump my application to Mongo 4.4, I wanted to reach out to the mailing list for a second opinion.

Are there any problems with using reactivemongo 1.0.3 with mongo 4.4?
Are there any plans to "officially" support mongo 4.4 in reactivemongo?

Thanks in advance!

[Cédric Chantepie]

Hi,

MongoDB 4.4 comes with no protocol changes, and very few command changes, so it should.

I personally use it in Atlas.

It's not written as supported because it requires to update the CI, and it seems that locally 4.4 can introduce latency/orresources issue.

[Cédric Chantepie]

All the driver tests are passing with 4.4.

That being said, MongoDB 4.4, outside custom/optimized clusters on Atlas can introduce significant performance regression (e.g. https://jira.mongodb.org/browse/SERVER-52619 ).