如何构建自动完成功能？

Question

功能类似

例如 我有一个叫人名的字段，当用户键入内容时，我们将显示与用户输入内容匹配的所有选项。

我的第一个问题：

which one should maintain trie tree, frontend, backend or both?

第二个问题：

No matter front end or back end, when will trie tree be loaded?
If trie loaded on start, million of entities loaded take a lot time, and huge data in memory.
If trie loaded once user searched, each time user typed is a DB call and a Rest call, which also consumme a lot resources. And at first search, user will see no options till he did once, which is bad user experience.

如果您有想法，请期待！