Appending quotes to CSV files of already exported quotes


I am looking at how to append quotes to already exported quotes in CSV files. I have a script similar to this and what I am wondering is how to first look into the file (if exists), get the last date of quotes already in a file and only append those dates up to today that are already not in the file?

I am asking this since it takes a lot of time to export all the symbols. I already see issues that this is not a smart thing to do actually for adjusted data for stocks and for continuous futures contracts…

Second question: would a Premium version of Amibroker with multiple threads running on a machine with PCIe SSD be any faster at exporting?


  1. Exporting everything (write only) is likely to be faster than reading/parsing/appending.

  2. Sure multiple threads work faster than single and you would get speed gains, but for any external data access you are limited by disk speed and disk IOPS (i/o operations per second)