Description:
This is just part of the broader $out project. The restrictions on the uniqueKey imposed by these code changes are like the description says:
In the "uniqueKey" spec:
- no duplicate keys
- no nested objects (use the dotted "nested.field" syntax instead)
- all fields must have value 1
At runtime:
- Each document must have every field of the uniqueKey. No fields of the uniqueKey may be missing, null, undefined or an array.
Engineering Ticket Description:
- Duplicate keys
- No nested objects
- All fields must have value '1'
- None of the values may be nullush