Support subkey index for Parse Schema indexes

[Moumouls]

New Feature / Enhancement Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.

Current Limitation

Parse Server do not support via Parse Schema the subkey index

Feature / Enhancement Description

Allow subkey index at parse index validation

Example Use Case

{indexes: { 'anArrayField.aKeyIntoAnElement': 1} }
Mongo example: https://docs.mongodb.com/manual/core/index-multikey/

Alternatives / Workarounds

Use the mongo client directly

3rd Party References

Mongo example: https://docs.mongodb.com/manual/core/index-multikey/

It seems that postgres support the feature but not sure if it will work: https://stackoverflow.com/questions/17807030/how-to-create-index-on-json-field-in-postgres

[parse-github-assistant]

Thanks for opening this issue!

• 🎉 We are excited about your ideas for improvement!