On 9/19/24 13:56, Paul Foerster wrote:
On 19 Sep 2024, at 17:14, Tom Lane <tgl@xxxxxxxxxxxxx> wrote:
Maybe. We don't really track glibc changes, so I can't say for sure,
but it might be advisable to reindex indexes on string columns.
Advisable is a word I undfortunately can't do much with. We have
terabytes and terabytes of data in hundreds of databases each having
potentially hundreds of columns that are candidates. Just reindexing
and taking down applications during that time is not an option in a
24x7 high availability environment.
See my thread-adjacent email, but suffice to say that if there are
collation differences that do affect your tables/data, and you allow any
inserts or updates, you may wind up with corrupted data (e.g. duplicate
data in your otherwise unique indexes/primary keys).
For more examples about that see
https://joeconway.com/presentations/glibc-SCaLE21x-2024.pdf
An potential alternative for you (discussed at the end of that
presentation) would be to create a new branch based on your original
SLES 15.5 glibc RPM equivalent to this:
https://github.com/awslabs/compat-collation-for-glibc/tree/2.17-326.el7
The is likely a non trivial amount of work involved (the port from the
AL2 rpm to the RHEL7 rpm took me the better part of a couple of days),
but once done your collation is frozen to the specific version you had
on 15.5.
--
Joe Conway
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
