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Hello,
That's funny. People misled by advertising start repeating all what they heard on the ad.
So for your information: web pages and other "services" offering "second scans"
give you a bunch of "hard coded" / precomputed scans - they run a dozen of scans on their
servers periodically and what you see is NOT result of actual scan being
performed in real time but just the display of somethign that was prepared earlier
and stored in the file. Or they display a query over database with some fixed
indexed field (like % change or something) - the same. What they offer is all hard coded / precalculated.
Now if you want to run REAL scan using CUSTOM formula you need to actually
EXECUTE this on the data.
Now to these 8 minutes for entire US database - it is relatively fast. It would be much faster if you
used NATIVE AmiBroker database, not external one, as AmiBroker mostly waits
for data from external source. The same scan using native database with enough
ram should take about one minute.
If you for example have 15000 symbols and each has 2600 quotes and say that your scan involves
only single MACD to calculate it you need to access 39 million quotes (2496 megabytes) and perform 78 million multiplications
and additions. Computation is not really a problem but reading the data (2.5 GB) is actually quite a task.
Try just COPYING 2.5GB of data (take such a file and copy it) and you will see it takes one minute.
So AmiBroker using NATIVE database runs with speed of hard disk copy. Which means that actual
processing takes almost nothing.
And this is actually best speed you will get from any software (of course considering
only softwares that perform actual computations, not merely display pre-computed files stored on disk).
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: "Gerald Monks" <glmonks@xxxxxxxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Monday, July 23, 2007 6:26 PM
Subject: [amibroker] Explorations/Scans are really slow...
> It takes between 8-10 minutes to complete an exploration (a simple one
> at that) of all US stocks. My EOD database is from Quotes Plus. Is
> this normal? For example, a comparatively complex scan of all US
> stocks with StockFetcher (over the internet of course) only takes
> around 4-5 seconds.
>
> Do I have a wrong setting somewhere in AB?
>
> Thanks
>
>
>
>
> Please note that this group is for discussion between users only.
>
> To get support from AmiBroker please send an e-mail directly to
> SUPPORT {at} amibroker.com
>
> For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
> http://www.amibroker.com/devlog/
>
> For other support material please check also:
> http://www.amibroker.com/support.html
>
> Yahoo! Groups Links
>
>
>
>
>
Please note that this group is for discussion between users only.
To get support from AmiBroker please send an e-mail directly to
SUPPORT {at} amibroker.com
For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
http://www.amibroker.com/devlog/
For other support material please check also:
http://www.amibroker.com/support.html
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