What is RethinkDB?
UPDATE: Several months after I wrote this post, RethinkDB was relicensed. For the CoCalc project, it was too late, and by then we had already switched to PostgreSQL.
Three Types of Open Source ProjectsThere are many types of open source projects. RethinkDB was the type of open source project where most work on RethinkDB has been fulltime focused work, done by employees of the RethinkDB company. RethinkDB is licensed under the AGPL, but the company promised to make the software available to customers under other licenses.
Academia: I started the SageMath open source math software project in 2005, which has over 500 contributors, and a relatively healthy volunteer ecosystem, with about hundred contributors to each release, and many releases each year. These are mostly volunteer contributions by academics: usually grad students, postdocs, and math professors. They contribute because SageMath is directly relevant to their research, and they often contribute state of the art code that implements algorithms they have created or refined as part of their research. Sage is licensed under the GPL, and that license has worked extremely well for us. Academics sometimes even get significant grants from the NSF or the EU to support Sage development.
Companies: I also started the Cython compiler project in 2007, which has had dozens of contributors and is now the defacto standard for writing or wrapping fast code for use by Python. The developers of Cython mostly work at companies (e.g., Google) as a side project in their spare time. (Here's a message today about a new release from a Cython developer, who works at Google.) Cython is licensed under the Apache License.
What RethinkDB Will BecomeRethinkDB will no longer be an open source project whose development is sponsored by a single company dedicated to the project. Will it be an academic project, a company-supported project, or dead?
A friend of mine at Oxford University surveyed his academic CS colleagues about RethinkDB, and they said they had zero interest in it. Indeed, from an academic research point of view, I agree that there is nothing interesting about RethinkDB. I myself am a college professor, and understand these people! Academic volunteer open source contributors are definitely not going to come to RethinkDB's rescue. The value in RethinkDB is not in the innovative new algorithms or ideas, but in the high quality carefully debugged implementations of standard algorithms (largely the work of bad ass German programmer Daniel Mewes). The RethinkDB devs had to carefully tune each parameter in those algorithms based on extensive automated testing, user feedback, the Jepsen tests, etc.
That leaves companies. Whether or not you like or agree with this, many companies will not touch AGPL licensed code:
"Google open source guru Chris DiBona says that the web giant continues to ban the lightning-rod AGPL open source license within the company because doing so "saves engineering time" and because most AGPL projects are of no use to the company."This is just the way it is -- it's psychology and culture, so deal with it. In contrast, companies very frequently embrace open source code that is licensed under the Apache or BSD licenses, and they keep such projects alive. The extremely popular PostgreSQL database is licensed under an almost-BSD license. MySQL is freely licensed under the GPL, but there are good reasons why people buy a commercial MySQL license (from Oracle) for MySQL. Like RethinkDB, MongoDB is AGPL licensed, but they are happy to sell a different license to companies.
With RethinkDB today, the only option is AGPL. This very strongly discourage use by the only possible group of users and developers that have any chance to keep RethinkDB from death. If this situation is not resolved as soon as possible, I am extremely afraid that it never will be resolved. Ever. If you care about RethinkDB, you should be afraid too. Ignoring the landscape and culture of volunteer open source projects is dangerous.
A ProposalI don't know who can make the decision to relicense RethinkDB. I don't kow what is going on with investors or who is in control. I am an outsider. Here is a proposal that might provide a way out today:
PROPOSAL: Dear RethinkDB, sell me an Apache (or BSD) license to the RethinkDB source code. Make this the last thing your company sells before it shuts down. Just do it.
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