QA scenarios for Mongo DB

I am researching on the different ways QA validation can be done when the database is NO-SQL(Mongo Db). For e.g in case of normal ETL Testing, we have Count Validation, null Validation, Column Validation, Sample Data Validation etc. What all validations can be performed when the db is Mongo DB. Also please can you write the query syntax which will be used for performing the different validations.