Hi @MikeZheng-3371 Thank you for posting your question o Microsoft Q&A and for using Azure services.
My understanding is that you are looking to sync your on prem oracle db data with your Azure Mongo db on cloud and wants your sync to be done hourly or daily.
Options to migrate your on-premises or cloud data to Azure Cosmos DB
Copy data from or to MongoDB using Azure Data Factory or Synapse Analytics
Those are the docs with guidance. You’re going to need to denormalize the data, azure data factory is probably going to be your best bet.
Are you familiar with Data Factory.?
Regards,
Oury