openark-kit, Facebook Online Schema Change, and thoughts on open source licenses

September 16, 2010

MySQL@Facebook team have recently published an Online Schema Change code for non blocking ALTER TABLE operations. Thumbs Up!

The code is derived from oak-online-alter-table, part of openark-kit, a toolkit I'm authoring. Looking at the documentation I can see many ideas were incorporated as well. And of course many things are different, a lot of work has been put to it by MySQL@Facebook.

openark-kit is currently released under the new BSD license, and, as far as I can tell (I'm not a lawyer), Facebook's work has followed the license to the letter. It is a strange thing to see your code incorporated into another project. While I knew work has begun on the tool by Facebook, I wasn't in on it except for a few preliminary email exchanges.

And this is the beauty

You release code under open source license, and anyone can pick it up and continue working on it. One doesn't have to ask or even let you know. Eventually one may release back to the community improved code, more tested (not many comments on oak-online-alter-table in the past 18 months).

It is a beauty, that you can freely use one's patches, and he can then use yours.

And here is my concern

When I created both openark-kit and mycheckpoint, I licensed them under the BSD license. A very permissive license. Let anyone do what they want with it, I thought. However Facebook's announcement suddenly hit me: what license would other people use for their derived work?

The OSC has been release under permissive license back to the community (again, I am not a lawyer). But, someone else could have made it less friendly. Perhaps not release the code at all: just sell it, closed-source, embedded in their product. And I found out that I do not want anyone to do whatever they want with my code.

I want all derived work to remain open!

Which is why in next releases of code I'm authoring the license will change to less permissive and more open license, such as GPL or LGPL. (Of course, all code released so far remains under the BSD license).

  • hi.

    haven't you thought about this kind of situations before?
    I mean it's weird that you change your license, after somebody actually do-what-they-wanted-and-the license-allowed-to-do.


  • @Tyrael,
    Well, people change their minds 🙂
    I'm happy with the use made so far to my code. I have just realized how important it is for me that the code remains open: for me, for you, for everyone.

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  • though I'm not alleging anything about this exact case neither do I represent positions of affected parties, I just wanted to say that more restrictive licenses may be the reason your code will not be reused and you will not get attribution.

    also, GPL will not force people to opensource their modifications, so you will not win openness.

    whatever license you pick, it applies to redistribution only, and nobody is obliged to redistribute, only the method of redistribution is shaped by license texts.

  • Hi Domas,
    Thanks. You were sure careful to pick your words 🙂 No reason to.

    You are right that GPL will not force people to opensource their modifications, if they never release them.
    But should someone choose to distribute a commercial product, then he/she is affected by the GPL.

    "...more restrictive licenses may be the reason your code will not be reused..." - I need to think this over

    "...and you will not get attribution..." - this is not my concern. It's not a matter of glorification.


  • Hi Shlomi, I see your concern, and it's a valid one.

    However, I doubt that changing the license at this point will make much of a difference. As Domas pointed out, even the GPL won't stop people from modifying your work and not sharing their changes if they're not distributing anything (well, except if you would consider going with GNU AGPLv3 - So if they use your code for a product that is offered as a service, you still don't have any leverage on forcing them to release their modifications.

    Heck, many don't give a damn and even include GPLed code in the products they distribute. I don't want to know how many do it and get away with it, because it a) needs to be discovered and b) someone needs to challenge them on that. If you haven't assigned copyright of your code to the FSF, you would have to do this by yourself...

    So the sad reality probably is, that one can only hope that everybody plays by the rules as outlined by the license. And I think by keeping your code under BSD, you're setting a good precedent, as it's usually perceived as a much more "friendly" license with less strings attached, which encourages collaboration and contributions.

    I would be more concerned about the negative connotation that a sudden license change brings than a few free-riders that couldn't care less about what license the software is under they are incorporating in their products.


  • Thanks, Lenz, valid points. I'll give it further thought.

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  • ahoka

    This license change makes no sense at all.

  • shlomi,

    just fyi if you don't pick GPLv3 and I am a closed source company I take your code and use it internally and forget about this circus with licenses as many ppl said above.

    so if the license won't protect your code against evil what is the right attitude?

    i think to use the less restictive license like MIT/BSDL

    this won't prevent anybody in FOSS community to use your code

    using viral licenses(like gplv3) is not really nice from my point of view

  • Istvan,
    Yes, of course in-house code doesn't have to do anything. That's OK.

  • Thank you all for your valued comments and input.
    I will meanwhile refrain from making changes to projects already released by BSD, until I get to consider in more depth the implications.

  • ahoka

    To ellaborate my eariler comment: you just proved that BSDL works! And you change to a viral license now? 🙂

  • stargazer

    Please note that what you wrote will always stay as free as you made it, someone else will not make it vanish by doing something with the code and not publishing their own changes to it.

    Also, ask yourself if you would rather have someone redo the work you did, possibly less well, than use your work to build on when they are not going to contribute back. For myself, the answer is that I'd rather have people spend time on new code and re-use what has been done once well enough.

  • stargazer how does the original code get vanished if somebody fork it and doesn't give it back to the community?

    it is obviously not true what you are saying, and what I pointed out earlier there is no license will protect you from an in-house usage by any company. how can you prove that somebody is using your code if there is no public visible sign of it?

  • stargazer, sorry i got it wrong what you wrote, i was in rush

    i agree with you

  • Vitaly Karasik

    Shlomi, many thanks for your openark-kit, especially for oak-chunk-update.
    I'm going to delete about 70-80% from 50M records InnoDB table in production environment. So oak-chunk-update should save me at least 3-4 hours of downtime.

    Vitaly [I was on you mysql performance course last year]

  • @Vitaly,
    Good to know it is being put to good use!

  • Shlomi,

    There is a very important philosophical reason to use the GPL. My next bit may sound too self important or the like, but philosophy is like that.

    Here is a claim: Human progress is made up of mechanisms in society which make people co-operate more when they short term interest is to co-operate less. Usually this also involves serving some of the other self-interests that these people have (in the end people always serve their own self interest).

    - marriage: the father (usually) would leave the mother after childbirth. In early societies we would be huddled in clans and so the clan would, communaly, take care of the infant. But today there are no communities like that so the marriage idea was born in order for the mothers and childs right to be protected. Ofcourse it gives some guarantees to the father too. But in essense the marriage concept is about trying to force fathers to co-operate with their families.

    - law and police: forcing all people to co-operate (sometimes against their will!).

    - taxes: no one likes paying them but there would be no state without them.

    - the UN: trying, by force of groups of states, to force states into co-operation.

    - capitalism - trying to encourage people to serve their own ends not by killing other people but rather by selling things to them. This selling of products usually forces one who wants to go down that road to form a company which is a bunch of people co-operating. With no incentive for profit this would not have happened.

    And finally the GPL. The GPL forces (again, not in all situations) co-operation amongst people making software. They may not like it at times (as they may not like taxes) but in the long run their interests are served better by the GPL than the BSD license.

    So there is a very important philosophical reason to prefer the GPL


    PS. The different between co-operating against my will opposed to co-operating out of consent is not as important as some people would like to believe (if I park my car in the right spot because I payed a fine previously and would like to avoid a further fine am I doing it out of my "free will" or out of "forcing" by the government ? Probably both. But it does not really matter which as long as large groups of people co-operate...).

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