Replace old documents

in My application Every day 6 times (4hrs per run) index will be updated by latest exchange rates documents.
Any one could guide me on best approach how to delete my old documents (having SourceCurrency=USD) from logstash and insert new documents to elasticsearch (for SourceCurrency=USD)?

  1. I have multiple documents for same SourceCurrency=USD.

Capture

  1. I dont want to update price document. I have to delete all old price documents having (SourceCurrency=USD) and then new document should be inserted ( since every run number of documents will vary for same SourceCurrency=USD)
  2. there is no document_id i havent defined. i cant create document id with combination of SourceCurrency+DestinationCurrency since i may not sure will get same number of destination currency all time. i dont want to retain the destination currency which is not received in latest run.