Ken, One note: after you change cache settings it is advised to restart AmiBroker. This is just to be sure that cache size change really takes place. I don't remember right now if growing isn't "on-the-fly" but as far as I remember it won't shrink it without restart.
>Number of bars: 50000. Wow! That's too much for FastTrack EOD. EOD databases should use 260 bars PER YEAR. So if you have 20 years it is 5200 bars. Specifying too high number here causes unnecessary big memory allocations that would certainly impact the performance. Best regards, Tomasz Janeczko amibroker.com ----- Original Message ----- From: Ken Close To: [email protected] Sent: Monday, July 07, 2008 6:04 PM Subject: [amibroker] Local vs External Database Storage Some of you may have read a number of recent exchanges I made with others about the speed of execution of a particular piece of code which did "ordinal rankings". I complained that Watchlists with 450 or so symbols were taking hours and Tomasz and Paul Ho wrote back and said that they were experiencing execution times on the same code in the order of minutes. After doing all sorts of things, and seeing no meaningful changes to the execution times, I decided to experiment with my database source. My only (current) database source is the FastTrack database. My database settings are FastTrack database plugin, Local data storage: disabled, Number of bars: 50000. I have previous subscribed to QuotesPlus, and while I ended my subscription in Oct of 2007, lazy me still had the database installed with the following settings: QuotesPlus plugin; Local data storage: enabled; Number of bars: 100000 (ha, I get too zealous with the zero key). A run with the same code, on approximately the same size Watchlist (452 members) showed Paul Ho's original code (single indicator) to complete in about 45 seconds, while my modified code (two indicators) was on the way to completion in about 22 minutes compared to the 1 hour 30 to 50 minutes I was seeing with the FastTrack database. So I am left to wonder whether the FastTrack plugin and its interface with the FastTrack data is the reason the retrieval is so slow compared to the QuotesPlus plugin. Or, whether the Local Storage enabled is the key factor. Further, I suspect but am not sure that the number of bars I stick in the box has little to do with the access times (in this case of EOD data) but I am not sure. I would like to hear the pros (faster times) and cons (wasted HD space??) of having local storage enabled. Can some one share before I convert my FastTrack data to local storage for a test. Thanks for your advice. Ken
