[Bug]: no distinction between path and array subscript for json expr

[zhagnlu]

Is there an existing issue for this?

• I have searched the existing issues

Environment

- Milvus version: master 
- Deployment mode(standalone or cluster):
- MQ type(rocksmq, pulsar or kafka):    
- SDK version(e.g. pymilvus v2.0.0rc2):
- OS(Ubuntu or CentOS): 
- CPU/Memory: 
- GPU: 
- Others:

Current Behavior

for current json expr, not differ json path or array subscript, for example:
json['0'][0] means json key is '0', and next 0 is array subscript. json[0][0] means the first array's first element.
but now json['0'][0] and json[0][0] all convert key path to 0.0, and can not differ them.

for postgres, it use different string flag to split them like:
json->'0'->>0, first '0' means path, second 0 means array subscript.

for mysql, it also do it, like:
json_extract(data, '$.'0'[0]), using [0] to specify it is array subscript.

so, we also need to distinct these two situation.

Expected Behavior

No response

Steps To Reproduce

Milvus Log

No response

Anything else?

No response

[yanliang567]

/assign @zhagnlu
/unassign

[xiaofan-luan]

Don't quite understand this,
json['0'] means key as '0', json[0] means array offset 0, is there any problem with current design?