On 9/19/24 13:07, Joe Conway wrote:
> On 9/19/24 11:14, Tom Lane wrote:
>> Paul Foerster <paul.foerster@gmail.com> writes:
>>> we have SLES 15.5 which has glibc 2.31. Our admin told us that
>>> he's about to install the SLES 15.6 update which contains glibc
>>> 2.38.
>
>>> 2) Does the glibc update have any impact?
>> 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.
>
>
> Every glibc major version change potentially impacts the sorting of some
> strings, which would require reindexing. Whether your actual data trips
> into any of these changes is another matter.
>
> You could check by doing something equivalent to this on every
> collatable column with an index built on it, in every table:
>
> 8<-----------
> WITH t(s) AS (SELECT <collatable_col> FROM <some_table> ORDER BY 1)
> SELECT md5(string_agg(t.s, NULL)) FROM t;
> 8<-----------
>
> Check the before and after glibc upgrade result -- if it is the same,
> you are good to go. If not, rebuild the index before *any* DML is done
> to the table.
... and I should have mentioned that in a similar way, if you have any
tables that are partitioned by range on collatable columns, the
partition boundaries potentially are affected. Similarly, constraints
involving expressions on collatable columns may be affected.
--
Joe Conway
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
