On 4/8/20 7:35 AM, Jimmy Thrasher wrote:
I'm seeing some unexpected behavior when sorting some strings, and it indicates I don't fully understand how postgresql string sorting works.
As I understand it, postgresql sorts strings roughly like strcmp does: character by character based on encoding value.
In particular, I'm seeing the following. I would expect "< S" to come first, because "<" (0x3c) is less than ">" (0x3e).
```
supercatdev=# select unnest(array['> N', '< S']) as s order by s;
s
-----
> N
< S
(2 rows)
```
I've broken this down further:
```
supercatdev=# select '> N' < '< S';
?column?
----------
t
(1 row)
```
Am I missing something about how sorting works?
I believe you are looking for 'C' collation:
test=# select unnest(array[('> N' collate "C") , ('< S' COLLATE "C")])
as s order by s;
s
-----
< S
> N
(2 rows)
For more information see:
https://www.postgresql.org/docs/12/collation.html
Metadata:
- postgresql 9.5.19, running on Ubuntu 16LTS
- encoding, collate, and ctype are all UTF8 or en_US.UTF-8, as appropriate
Thanks!
Jimmy
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
