Hello,
during our tests of Postgres with ICU we found an issue with ILIKE of upper and lowercase sigma (Σ). The letter has two lowercase variants σ and ς (at the end of a word). I'm working with en_US and en-US-x-icu collations and results are a bit unexpected - they are inverted:
postgres=# SELECT
postgres-# 'ΣΣ' ILIKE 'σσ' COLLATE "en_US",
postgres-# 'ΣΣ' ILIKE 'σς' COLLATE "en_US"
postgres-# ;
?column? | ?column?
----------+----------
t | f
(1 row)
postgres=# SELECT
postgres-# 'ΣΣ' ILIKE 'σσ' COLLATE "en-US-x-icu",
postgres-# 'ΣΣ' ILIKE 'σς' COLLATE "en-US-x-icu";
?column? | ?column?
----------+----------
f | t
(1 row)
postgres-# 'ΣΣ' ILIKE 'σσ' COLLATE "en_US",
postgres-# 'ΣΣ' ILIKE 'σς' COLLATE "en_US"
postgres-# ;
?column? | ?column?
----------+----------
t | f
(1 row)
postgres=# SELECT
postgres-# 'ΣΣ' ILIKE 'σσ' COLLATE "en-US-x-icu",
postgres-# 'ΣΣ' ILIKE 'σς' COLLATE "en-US-x-icu";
?column? | ?column?
----------+----------
f | t
(1 row)
I run those commands on the latest (14.1) official docker image.
Is it possible to unify the behaviour?And which one is correct from the community point of view?
If I could start, I think both results are wrong as both should return True. If I got it right, in the background there is a lower() function running to compare strings, which is not enough for such cases (until the left side isn't taken as a standalone word).
Thanks,
- jj
