postgresql/lightdb中的collation实现、对order by的影响及与oracle/mysql异同点，c实现库参考

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://juejin.cn/post/6995758217384951822

https://help.aliyun.com/document_detail/52950.html

https://blog.csdn.net/ctypyb2002/article/details/106429295

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、且平台无关（也就是不使用libc的c实现，postgresql 17完全内置的实现了icu的collation，见https://www.postgresql.org/about/news/postgresql-17-released-2936/），IBM全系采用，从AIX到DB2到jdk。也就是gnu libc的实现是依赖于平台和版本的，不同的平台确实可能返回不同的顺序。

https://www.cnblogs.com/tiny1987/p/16382975.html

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