用于索引的Cloud Firestore通配符
问题描述：
设置索引时，Cloud Firestore中通配符级别的语法是什么?我知道有一个安全规则.
What is the syntax for a wildcard level in Cloud Firestore when setting up indexing? I know there is one for security rules.
谢谢.
答
Cloud Firestore索引基于集合名称，而不是完整的集合路径.因此，如果要在users/{id}/messages上创建索引，正确的方法是在messages上创建索引.
Cloud Firestore indexes are based on collection names, not full collection paths. So if you want to create indexes on users/{id}/messages, the correct way to do this is to create an index on messages.
所有同名的集合，即使嵌套在文档下，也共享相同的索引.
All same-named collections, even if nested under documents, share the same indexes.