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Tomasz,
You asked about what type of database VectorVest uses. I am just a VV
user who is not a programer so what follows is a combination of
observations and a couple guesses as to what the database structure
might be. I hope it helps give you an idea about VV and how easy (or
hard) it might be to give AB the ability to use VV's unique
indicators. It is these unique indicators that attracts me to VV.
What VV lacks is great charting and automated backtesting, both of
which AB has. I would like to be able to use AB to access 5 or 6 of
the most useful indicators unique to VV.
VV is primarily a stock ranking system and as such it can quickly
rank and re-rank 7,000 stocks in a couple seconds. It is very fast at
this. If I select another date, it takes about twice as long to do
the first ranking of 7,000 stocks for the new date, subsequent re-
ranking for the new date regains the speed. If I ask for a price
chart of a single stock VV can take several seconds to diaplay. So my
guess is the VV database is structured for easy comparison of stocks
on a given date. I have no idea of how that might be implimented. I
have heard someone say the VV database looks like a MS Access
database, but I have no way of knowing whether this is good or bad or
even if it is true.
Another note: When a new day's quotes are downloaded, the user has
the option of "compacting" the database at once or using the database
right away. Compacting takes a some time so sometimes it is only down
once every 7 to 10 days. VV continues to work although a bit slower
until compacting is done. My guess is that VV appends the new data
when downloading and thus fragments the VV database more and more
with each download until a compacting is done. So it might be much
easier to program AB to just access "compaced" database. I would
gladly compact my VV database daily to be able to use it with AB.
Another observation: VV downloads include changes as well as price
updates. new stocks are added (that is fine with me), and merged
stocks are deleted (which is not to my liking). I wish VV would leave
in merged stocks to make backtesting more realistic. One of the great
things I like about AB is the ability to maintain a more complete
stock universe for backtesting. Thus, if I was given a choice in how
AB might handle VV data, I would prefer to see AB extract VV data and
place this in AB's own data files (so VV could not delete merged
stocks). On the other hand, if this would be difficult, I would still
be very pleased to be able to use AB if it just worked directly on
the VV database.
This post is already a bit long so I will put a list of the VV stocks
indicators in a followup post.
b519b
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