On Fri, Feb 14, 2014 at 05:02:26PM -0500, Bruce Momjian wrote: > On Thu, Feb 13, 2014 at 09:47:01PM -0500, Bruce Momjian wrote: > > On Wed, Oct 16, 2013 at 02:17:11PM -0400, Bruce Momjian wrote: > > > > > You can see the UTF8 case is fine because \n is considered greater > > > > > than space, but in the C locale, where \n is less than space, the > > > > > false return value shows the problem with > > > > > internal_bpchar_pattern_compare() trimming the string and first > > > > > comparing on lengths. This is exactly the problem you outline, where > > > > > space trimming assumes everything is less than a space. > > > > > > > > For collations other than C some of those issues that have to do with > > > > string comparisons might simply be hidden, depending on how strcoll() > > > > handles inputs off different lengths: If strcoll() applies implicit > > > > space padding to the shorter value, there won't be any visible > > > > difference in ordering between bpchar and varchar values. If strcoll() > > > > does not apply such space padding, the right-trimming of bpchar values > > > > causes very similar issues even in a en_US collation. > > > > I have added the attached C comment to explain the problem, and added a > > TODO item to fix it if we ever break binary upgrading. > > > > Does anyone think this warrants a doc mention? > > I have done some more thinking on this and I found a way to document > this, which reduces our need to actually fix it some day. I am afraid > the behavioral change needed to fix this might break so many > applications that the fix will never be done, though I will keep the > TODO item until I get more feedback on that. Patch attached.
Patch applied. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. + -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers