Appending quotes to CSV files of already exported quotes

AFL Programming
#1

Hi,

I am looking at how to append quotes to already exported quotes in CSV files. I have a script similar to this http://www.amibroker.com/kb/2014/11/14/how-to-export-quotes-to-separate-text-files-per-symbol/ 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?

Thanks.

#2

  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)