>Number of bars: 50000.
----- Original Message -----
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