At Thu, 4 Aug 2022 19:01:33 +0900, 荒井元成 <n2...@ndensan.co.jp> wrote in > Thank you for your reply. > > SQLServer supports Unicode Variation Selector, so I would like PostgreSQL to > support them as well.
I studied the code a bit further, then found that simple comparison can ignore selectors by using nondeterministic collation. CREATE COLLATION col1 (provider=icu, locale='ja', deterministic=false); SELECT (U&'\+003436' || U&'\+0E0101' || U&'\+00304D' collate col1) = U&'\+003436' || U&'\+00304D'; ?column? ---------- t However LIKE dislikes this. > ERROR: nondeterministic collations are not supported for LIKE Deterministic collations assume text equality means bytewise equality. So, the "problem" behavior is correct in a sense. In that sense, those functions that do not support nondeterministic collations can be implemented without considering ICU, which leads to the "problem" behavior. ICU has regular expression function so LIKE might be ableto be implemented using this. If it is done, and if a non-deterministic IVS-sensitive collation is available (I didin't find how to get one..), LIKE would work as you expect. But.. regards. -- Kyotaro Horiguchi NTT Open Source Software Center
