Somebody should teach me how to accept community contributions. On Friday I looked at the second version of a community contributed patch. I.e. it was since then re-written. It’s Bug#20837, and it again is an infrastructure issue that is identical in all our forks.
(I won’t go into the details how the bad piece of code got into 5.0 in the first place, people who were in charge back in 2004 are now all gone.)
My experience suggests that quality is an issue with almost every piece of code that’s thrown at us (MariaDB team contributions are an exception, since they are made by ex-MySQLers). Should a semi-working, semi-documented code be accepted, expecting that there will be more patches? In that environment it would be impossible to plan for stable versions (if you mean it).
Perhaps the reason for low contributed code quality is that MySQL ecosystem is mostly made by DBAs, not C/C++ engineers. Perhaps through more documentation, standardization, re-engineering we can get better results.
On the other hand, MySQL has a fairly large community of engines. Indeed, we have more than a dozen of fairly significant storage engines. There were no contributions from this group of any significance.