关键词 bitmap 位图

@Numbcoder uuid 优势就是简单😂不过还是得分数据库，postgres 支持 uuid 类型，用 16 字节存储 binary 数据。不是聚簇索引效率不会很差，肯定比不过自增 id 就是了

mysql 主键 clustered index 用 uuid 简直是灾难

用 HikariCP

https://github.com/brettwooldridge/HikariCP

这个得根据数据量来看会扩充多少次吧
java stream api 是可以指定 downStream 的

之前 ftw 3080 就有 boom 的了，好多人都无脑刷 bios

都是伪需求，一页 100 条也得 7w 页，你会去看第 6w 页的数据嘛？

https://tech.meituan.com/2014/03/06/in-depth-understanding-string-intern.html

推荐用 guava 的 Interner

语言方面《 Thinking In Java 》和《 Effective Java 》两本书足以，JVM 书没怎么看过

postgres
https://github.com/digoal/blog/blob/61bbe29d6f06bb9b98b7a694f2180ffd33987835/201712/20171205_02.md

select 的 column 不应该是在 group by 里吗？

https://dev.mysql.com/doc/refman/8.0/en/group-by-handling.html

If ONLY_FULL_GROUP_BY is disabled, a MySQL extension to the standard SQL use of GROUP BY permits the select list, HAVING condition, or ORDER BY list to refer to nonaggregated columns even if the columns are not functionally dependent on GROUP BY columns. This causes MySQL to accept the preceding query. In this case, the server is free to choose any value from each group, so unless they are the same, the values chosen are nondeterministic, which is probably not what you want. Furthermore, the selection of values from each group cannot be influenced by adding an ORDER BY clause. Result set sorting occurs after values have been chosen, and ORDER BY does not affect which value within each group the server chooses. Disabling ONLY_FULL_GROUP_BY is useful primarily when you know that, due to some property of the data, all values in each nonaggregated column not named in the GROUP BY are the same for each group.

map 维护起来真的是…还是写个类维护吧…validator 可以做分组校验

这种除非一开始设计的非常好，否则就是给自己挖坑

手动创建 Flyway，然后跑 Flyway.migrate ？