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MySQL & Open Source Code Quality
dozek writes "Perhaps another rung for the Open Source model of software development, eWeek reports that an independent study of the MySQL source code found it to be "in fact six times better than that of comparable commercial, proprietary code." You can read the eWeek write-up or the actual research paper (reg. required)."
Six times better? I didn't know it was possible to quantify code quality in that matter. Interesting.
"Nature doesn't care how smart you are. You can still be wrong." - Richard Feynman
Perhaps another rung for the Open Source model of software development
Uhh... no.
It's is a glowing report for this particular open source project but that brush shouldn't be used to paint all open source. That will just lull open source developers into a false sense of euphoric contentment. Code quality didn't get this far by having a fixed target, that target should be a carrot on a stick that will never quite be reached.
Trolling is a art,
Undoubtedly()
{
when();
you = measure(quality);
in.defects();
per->lines_of(code, anyone);
can = write(good, solid, code);
}
I agree with you that you can't simply measure quality but...
If you just RTFA, you'll see that is not "6 times better" but "6 times less bugs found then the average on commercial products"
The only thing wrong in the article:
They should replace the term "commercial" with "closed source", because Mysql is also a commercial product and what makes it different is the open source model.
"Defect" is also a difficult term to define. Some errors are much worse than others. It's not all about numbers, folks. Don't get me wrong, I'm not saying that MySQL isn't a great product. I just get skeptical when I hear things talked about in terms of "better" and "best."
"Nature doesn't care how smart you are. You can still be wrong." - Richard Feynman
I do believe that Open Source is better than proprietory. Faults per 1000 lines of code may seem like a valid scale, but I think it is indicatory at best, not proof.
* It does not take into account the design of the software. This is often as important as the actual quality of the code.
* It does not take into account the kind of errors. This is related to the first, but a buffer overflow that allows root access is worse than a failed instruction.
* It does not even take the length of lines into account. Shortening the lines could lower the number, without actually changing anything.
So, small victory, but the race goes on.
the pun is mightier than the sword
This just looks like some quasi-scientific statement, trying to express things as a number that really don't fit such a representation. For example, as the number of defects decreases, it becomes increasingly more difficult to find the ones that are left. And is code that contains no bugs at all infinitely much better than code that contains a single bug which hardly ever occurs?
I'm under the impression that most "bugs" in software (certainly most bugs in my code) aren't bugs like these in the article (null dereferences, uninitialized variables, etc), but they're algorithm bugs. As in, there's a subtle interplay between different parts of complicated algorithms that can be easy for programmers to miss. Those types of bugs are going to be much harder to find, and certainly not going to be found in analysis such as this one.
Not only is it hard to define defect (and it is very obvious that some defects are worse than others), but this code review sounds like it only spots "grammatical" or style errors in the code. It doesn't sound like it could find a defect in an algorithm implementation or logic. To me, these are where the true defects are, in the logic/reasoning breakdowns.
Geek used to be a four letter word. Now it's a six-figure one.
0.09 vs 0.53 bugs/KLOC can also mean mysql has six times the amount of code per line, compared to an average "commercial" program. Those numbers should be divided by a code-density-factor.
I'm not sure what you mean by "grammatical" or style errors. If you're talking about syntax errors, those should prevent the code from compiling. I'm not aware of how coding style can be an error (unless you're programming in Python).
The specific errors in MySQL were dereferencing null pointers, failure to deallocate memory (memory leaks), and use an uninitialized variable. These aren't the only bugs that such an analysis can find; they're the ones that were found in MySQL. And they're definitely errors in logic.
Certainly, there are bugs that such an analysis can't find. If you define PI as 3.15, your calculations are going to be off. If you create a function to determine the circumference of a circle as 2 * PI * Diameter, you've got a bug. I suspect that those are the types of errors in logic that you were referring to, and you're right that they will not be caught by a code analysis. However, that doesn't mean that comparing the frequence of the errors that CAN be caught between two programs is an invalid act. From my experience, programmers who make fewer of the former errors also make fewer of the latter. Analyzing catchable errors is a good metric for the frequency of errors in a given source tree, even if all errors aren't caught.
"The legitimate powers of government extend only to such acts as are injurious to others." Thomas Jefferson.
This is proof positive that the marketing engine has started churning in the Linux / Open Source arena. The quoted statistics are meaningless. Here are is a short list of things (in no particular order) that are wrong with this "study" (who paid for it anyway?):
Lines of code is meaningless as a reliable measure of anything. The most this number can be used for is for assessing the high level complexity (i.e. simple, non-trivial, or hard) of an application / code construct. It is absolutely pointless to compare two different applications against each other by lines of code. This means that you can say that one is non-trivial and the other is complex or you can say that both are complex, but there is no valid way of determining (by using this particular metric) that one application is more complex than the other. I believe this is the fundamental flaw in this "study".
The study igores capabilities. If application A has feature a, b, and c, and application B has features a, b, c, d, e, f, g, h , is it even meaningful to compare the number of defects detected between applications A and B? And no - normalizing it by lines of code is not valid (see previous point).
Testing methodology : from the defects quoted in the article, it appears as if they "study" did white box testing on MySQL. This is hardly complete. While null pointer dereferences are certainly terrible, I would be also very very concerned about bugs pertaining to SQL capabilites, data integrity, performance, etc. If I go out and do a comparison of RDBMS's for a client, my report wouldnt be complete at all without covering these areas. How come the "study" doesnt mention any of these things?
Lets face it : this is a paid propaganda article by the marketing machinery. Much like Microsoft has done in the past.
There is no such thing as luck. Luck is nothing but an absence of bad luck.
It is really embarassing to have bad code with your name on it, released to the public.
Not only that, but there is a small percentage of coders when presented with an ugly solution to a problem, will pretty it up, just "because". And it is a good way to get known in the OSS world.
Unlike the corporate world, working but ugly code is hidden deeper and deeper, and people go out of their way to avoid it.
A flawless implementation of a crap algorithm is still crap. I don't care if your bubble-sort routine has no memory leaks or buffer overruns; it still scales O(N^2). Likewise, a so-called "database" which does not implement key features like transactions and stored procedures is fundamentally flawed even if there are zero coding errors.
MySQL may be well-written, but it's still a piece of crap by the standards of any professional DBA.
Why is it that the proponents of "one nation under God" are so eager to get rid of "liberty and justice for all"?
Sorry, but my opinion is pretty strong on this. Going from anything Oracle to MySQL is NOT trivial.
Sorry, but until MySQL has a mode where ALL tables are transaction safe, or at least throws an error when you try to create a fk reference to a non-transaction safe table, it's transactions are too prone to data loss due to human error.
It's a good data store, but the guys programming it have to "get it" that transactions can't be optional in certain types of databases, and neither can constraints, or fk enforcement.
MySQL has a tendency of failing to do what you thought it did, and failing to report an error so you know. This is a legacy left over from being a SQL interpreter over ISAM files. It makes MySQL a great choice for content management, but a dangerous choice for transactional systems.
--- It is not the things we do which we regret the most, but the things which we don't do.
No it doesn't. It "proves" that on average, by line, MySQL has fewer errors in code. It says nothing of the severity of the errors in either package.
Furthermore- MySQL is not even close to being equal in feature set to almost any commercial DB; replication/backup sucks, it's not ACID compliant, it had no transaction support until recently, no stored procedures, no triggers.
How on earth could you possibly compare it to almost any commercial SQL DB which has all these...and say MySQL is better?
A lot of people knew that.
No, every two bit web designer thinks its the greatest thing since sliced bread, since they think a select w/group+sort is an advanced query. Every professional DBA I've met refuses to work with MySQL and/or hates it, and they can go on for an hour about why. When are you people going to realize that PostgreSQL is so much better than MySQL, save some incredibly risky performance options?
MySQL is awesome! But let's be careful about this story, okay? It's the over-generalization that gives OSS/Linux advocates a bad name ("The Gimp is equivalent to Photoshop!").
But you just said "This proves that MySQL is better than commercial offerings!"
Please help metamoderate.
Porting between dbms products depends primarily on two issues:
1. usage of vendor extensions
2. usage of standard relational functionality
Generally speaking, if you've minimized #1 in your application you can easily port between Oracle, DB2, SQL Server, Sybase, Postgesql, etc: sure, you could hit some issues with jdbc drivers, and may need to port a few idioms (partitioning for example), but it shouldn't be a killer. But going from any of the above list to mysql isn't suggested: you'll get hung up on #2 (it doesn't support standard SQL or DDL)
Realistically, if I wanted to go to a less expensive product than oracle I'd look down this list:
- db2 (1/3 to 1/2 oracle cost)
- sybase (cheaper than oracle, but dwindling market share)
- firebird (very low cost)
- postgresql (free)
All of the above are mature relational databases that you could port oracle applications from.
But you mentioned 'mission critical'. At this point I'd be very cautious about either postgesql or mysql in a mission-critical role. How important is it to you that you can recover 100% of your data in the event of a database crash? I'd put my money (and career) on db2 or oracle delivering that kind of quality over mysql...
It does indeed sound a bit like that, and with good reason. If you notice, the "indepedent review" was carried out by Reasoning, Inc., and we've heard of them before in these parts.
For the benefit of those who haven't seen this trollfest^H^H^H^H^H^H^H^H^Hstory in its previous incarnations, Reasoning's services spot what some people call "systematic" errors, things like NULL pointer dereferencing or the use of uninitialised variables. As many people note every time this subject comes up, any smart development team will use a tool like Lint to check their code anyway, as a required step before check-in and/or as a regular, automated check of the entire codebase, and so any smart development team should find all such errors immediately. IOWs, it's grossly unfair to compare open and closed source "code quality" on this basis. Any project that has errors like this in it at all isn't serious about quality, and it shouldn't take an external study to point this out.
Serious code quality is not dictated by how many mechanical errors there are that slip through because of weaknesses in the implementation language. Rather, it is indicated by how many "genuine" logic errors -- cases where the output differs unintentionally from the specifications -- there are. Of course, no automated process can identify those, but to get a meaningful comparison of code quality, you'd need to investigate that aspect, rather than kindergarten mistakes.
There are other objections to their principal metric as well. For starters, source code layout is not normally significant in C, C++ or Java, so any metric based on line count is going to be flawed at best. But the big objection is that they're talking about childish mistakes, and comparing supposedly world class software based on childish mistakes isn't helpful (except to dispel the myth that some big name products have sensible development processes).
If you disagree, post your argument. (-1, Overrated) isn't your personal censorship tool for views you don't like.