[Feature]: Support Routing policy as elastic search.

[xiaofan-luan]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe.

By default, both elastic and Milvus use primary key or id to shard data.

However, under some use cases, user specified routing could be really helpful.

For example, under multi tenant use case, one tenant data is usually limited and can be put into the same shard. This could help the performance of groupby and clustering compaction.

Also, the routing policy could help the potential shard split in the future.

Describe the solution you'd like.

No response

Describe an alternate solution.

No response

Anything else? (Additional Context)

No response

[xiaofan-luan]

/assign @xiaocai2333

[xiaofan-luan]

And of course, by introducing customized routing policy,
Delete, Upsert, Query and search, you need to specify routing key.