Re: pgsql 10.23 , different systems, same table , same plan, different Buffers: shared hit - Mailing list pgsql-performance

Achilleas Mantzios <a.mantzios@cloud.gatewaynet.com> writes:
> Thank you, I see that both systems use en_US.UTF-8 as lc_collate and 
> lc_ctype,

Doesn't necessarily mean they interpret that the same way, though :-(

> the below seems ok

> FreeBSD :

> postgres@[local]/dynacom=# select * from (values 
> ('a'),('Z'),('_'),('.'),('0')) as qry order by column1::text;
> column1
> ---------
> _
> .
> 0
> a
> Z
> (5 rows)

Sadly, this proves very little about Linux's behavior.  glibc's idea
of en_US involves some very complicated multi-pass sort rules.
AFAICT from the FreeBSD sort(1) man page, FreeBSD defines en_US
as "same as C except case-insensitive", whereas I'm pretty sure
that underscores and other punctuation are nearly ignored in
glibc's interpretation; they'll only be taken into account if the
alphanumeric parts of the strings sort equal.

            regards, tom lane