Let me double check that assertion before we go too far with it. Most of the problems I've seen are across 5 and 6 boundaries. I thought I had case where it was within a minor release but I can't find it right now. I'm going to dig.
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That being said the sort order changes whether you statically or dynamically link (demonstrated on 4+ machines running different linux flavors), so at the point I have no reason to trust the stability of the sort across any build. I legitimately question whether strcoll is buggy. Ex. I have cases where for three strings a, b and c: a > b, but (a || c) < (b || c). That's right postfixing doesn't hold. It actually calls into question the index scan optimization that occurs when you do LIKE 'test%' even on a single machine, but I don't want to bite that off at the moment. My mentality has switched to 'don't trust any change until shown otherwise', so that may have bled into my last email. - Matt K. On Sep 17, 2014, at 8:17 AM, Robert Haas <robertmh...@gmail.com> wrote: > On Wed, Sep 17, 2014 at 9:07 AM, Matthew Kelly <mke...@tripadvisor.com> wrote: >> Here is where I think the timezone and PostGIS cases are fundamentally >> different: >> I can pretty easily make sure that all my servers run in the same timezone. >> That's just good practice. I'm also going to install the same version of >> PostGIS everywhere in a cluster. I'll build PostGIS and its dependencies >> from the exact same source files, regardless of when I build the machine. >> >> Timezone is a user level setting; PostGIS is a user level library used by a >> subset. >> >> glibc is a system level library, and text is a core data type, however. >> Changing versions to something that doesn't match the kernel can lead to >> system level instability, broken linkers, etc. (I know because I tried). >> Here are some subtle other problems that fall out: >> >> * Upgrading glibc, the kernel, and linker through the package manager in >> order to get security updates can cause the corruption. >> * A basebackup that is taken in production and placed on a backup server >> might not be valid on that server, or your desktop machine, or on the spare >> you keep to do PITR when someone screws up. >> * Unless you keep _all_ of your clusters on the same OS, machines from your >> database spare pool probably won't be the right OS when you add them to the >> cluster because a member failed. >> >> Keep in mind here, by OS I mean CentOS versions. (we're running a mix of >> late 5.x and 6.x, because of our numerous issues with the 6.x kernel) >> >> The problem with LC_IDENTIFICATION is that every machine I have seen reports >> revision "1.0", date "2000-06-24". It doesn't seem like the versioning is >> being actively maintained. >> >> I'm with Martjin here, lets go ICU, if only because it moves sorting to a >> user level library, instead of a system level. Martjin do you have a link >> to the out of tree patch? If not I'll find it. I'd like to apply it to a >> branch and start playing with it. > > What I find astonishing is that whoever maintains glibc (or the Red > Hat packaging for it) thinks it's OK to change the collation order in > a minor release. I'd understand changing it between, say, RHEL 6 and > RHEL 7. But the idea that minor release, supposedly safe updates > think they can whack this around without breaking applications really > kind of blows my mind. > > -- > Robert Haas > EnterpriseDB: http://www.enterprisedb.com > The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
