On 12/12/2017 01:52 PM, Alexander Korotkov wrote: > On Tue, Dec 12, 2017 at 3:49 PM, Teodor Sigaev <teo...@sigaev.ru > <mailto:teo...@sigaev.ru>> wrote: > > Yes, the thing is that we change behavior of existing ~> > operator. In general, this is not good idea because it could > affect existing users whose already use this operator. > Typically in such situation, we could leave existing operator as > is, and invent new operator with new behavior. However, in this > particular case, I think there are reasons to make an exception > to the rules. The reasons are following: > 1) The ~> operator was designed especially for knn gist. > 2) Knn gist support for current behavior is broken by design and > can't be fixed. Most we can do to fix existing ~> operator > behavior as is to drop knn gist support. But then ~> operator > would be left useless. > 3) It doesn't seems that ~> operator have many users yet, > because an error wasn't reported during whole release cycle. > > I hope these reasons justify altering behavior of existing > operator as an exception to the rules. Another question is > whether we should backpatch it. But I think we could leave this > decision to committer. > > I think that this patch is ready for committer. > > I'm agree with changing behavior of existing ~> operator, but is any > objection here? Current implementation is not fixable and I hope > that users which use this operator will understand why we change it. > Fortunately, the fix doesn't require changes in system catalog. > > The single question here is about index over expression with this > operator, they will need to reindex, which should be noted in > release notes. > > > Yes. I bet only few users have built indexes over ~> operator if any. > Ask them to reindex in the release notes seems OK for me. >
Is there a good way to detect such cases? Either in pg_upgrade, so that we can print warnings, or at least manually (which would be suitable for release notes). regards -- Tomas Vondra http://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
