树状数据的存储

https://technobytz.com/closure_table_store_hierarchical_data.html

Closure Tables
https://coderwall.com/p/lixing/closure-tables-for-browsing-trees-in-sql

ClosureTable以一张表存储节点之间的关系，其中包含了任何两个有关系（上下级）节点的关联信息

https://kyle.ai/blog/6905.html

https://www.red-gate.com/simple-talk/databases/sql-server/t-sql-programming-sql-server/sql-server-closure-tables/

https://medium.com/m/global-identity?redirectUrl=https%3A%2F%2Ftowardsdatascience.com%2Fclosure-table-pattern-to-model-hierarchies-in-nosql-c1be6a87e05b

https://dirtsimple.org/2010/11/simplest-way-to-do-tree-based-queries.html

https://stackoverflow.com/questions/49700342/closure-table-equivalent-for-graph-structures-in-sql

https://github.com/developerworks/hierarchy-data-closure-table

drop box 的分表实现：
https://dropbox.tech/infrastructure/reintroducing-edgestore
https://dropbox.tech/infrastructure/alki–or-how-we-learned-to-stop-worrying-and-love-cold-metadata

树状格式存储总结：
http://index-of.es/Programming/Pragmatic%20Programmers/SQL%20Antipatterns.pdf

mongoDB的实现
https://docs.mongodb.com/manual/applications/data-models-tree-structures/

Facebook社交图谱TAO
TAO是Facebook核心数据-社交图谱的自研存储系统，英文原版论文：https://www.usenix.org/system/files/conference/atc13/atc13-bronson.pdf，发表于2013年。系统设计有一个很重要的原则就是以小为美，TAO无疑是一个很经典的案例。时隔多年，我们重新回顾下Facebook是如何利用成熟组件构建系统支持海量社交图谱需求的。
https://zhuanlan.zhihu.com/p/158361250

https://docs.microsoft.com/en-us/azure/architecture/patterns/sharding