MetaApi supports multi tenant

[BohuTANG]

Summary

It seems MetaApi is a global view, can not get a tenant database/table:

https://github.com/datafuselabs/databend/blob/dd7a004b6b9158769d79bd0502e4802bb53490a7/query/src/catalogs/backends/impls/meta_remote.rs#L79-L137

The KVApi works well with a prefix.

[drmingdrmer]

With tenant id, the namespace for a table would be tenant_id/user_id/database/table or tenant_id/database/table?
I.e., is it legal that two user have database with the same database name?

[ariesdevil]

IMO yes, two tenants can have the same database name and a tenant can have multiple users.
Correct me if I was wrong.

[BohuTANG]

For databend use case, tenant_id/database/table is ok, there is no user_id from catelog.