|My products will be only stocks.
Every stocks has always a trading code that i'll use as PK. For every stocks i need to store 2 kinds of fields:
1) Descriptive fields that changes rarely like: description, isin code, country, expiration
2) Prices fields like: last price, minimun, maximum
When I launch my app i will load my db data in my memory and i'll start to download prices from servers. I'll do calculation between the prices i've in memory and the price I receive from server and only when i'll click "Save" button i'll write data in my db....-