http://peter.eisentraut.org/blog/2022/09/26/icu-features-in-postgresql-15
https://www.postgresql.org/docs/current/collation.html
https://dba.stackexchange.com/questions/106964/why-is-my-postgresql-order-by-case-insensitive
https://www.appsloveworld.com/postgresql/100/80/oracle-vs-postgres-order-by
https://help.aliyun.com/document_detail/52950.html
https://www.postgresql.org/docs/current/sql-createcollation.html
https://wiki.postgresql.org/wiki/Collations
https://awide.io/postgresql-and-collation-what-changed-in-postgresql-10/
需要更新到lightdb vs postgresql
对于字符集转换，主要有icu和iconv两个库，前者强大的多，IBM全系采用，从AIX到DB2到jdk。
https://unicode-org.github.io/icu/userguide/icu4j/
https://unicode-org.github.io/icu/userguide/icu4c/
https://www.linuxfromscratch.org/blfs/view/7.8/general/icu.html