Most trading applications receive datafeed from commerical providers such as IQFeed or brokerages that support trading API. Is there merit in storing it in the local database? Intraday datafeed is just massive in size, and the database would grow exponentially with 1 minute data for just 50 stocks, never mind tick-by-tick data. I suspect this would be a nightmare for database backup and may impact performance.
If you get historical data in text files on DVD or online, then storing it in the database is the only logical choice, but would it be still a good idea if you get it through API?