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Bill,
I generally do base my comments on tested observations, especially
when posting on the subject to the UKB, which in this case I have
done.
I have carried out tests, along the lines suggested by you, in the
past.
However, I can and do make mistakes and also when answering forum
questions I often write from memory, which tends to fade a bit.
I made a check away back because I was confused about the way AQ
operated relative to my expectations of the logic of downloaders.
I believe the method has changed over the years so that is the source
of my confusion.
____________________________________________________________________
Per the AQ read me file:
WHAT'S NEW IN VERSION 1.67?
? fix: when user-selected 'from' date is earlier than last date
of quote available in AmiBroker then earlier date is used.
WHAT'S NEW IN VERSION 1.66?
last update date for each ticker individually is retrieved only if
database has less than 50 symbols. Otherwise the update date of the
first ticker is taken for all.This speeds up ticker list retrieval in
large databases.
___________________________________________________________________
Anyway, as long as Jim gets his data, and he will if he does as I
suggested. I think he would have got it anyway if he had kept
updating for three days (until enough bars to chart were accumulated).
I realised this after I posted but some people don't like me
extending my posts and also it takes up too much of my time to
correct all of my minor errors and oversights so I don't do it every
time.
brian_z
--- In amibroker@xxxxxxxxxxxxxxx, "wavemechanic" <timesarrow@xxx>
wrote:
>
> With respect to the update process, I don't use AQ at this time,
but when I did I do not recall any problem with different symbols
having different last dates (not holes in data) for auto update. My
impression was that AQ gets the earliest last available date for the
entire symbol list (I suspect this would be easier and faster than
keeping track of individual ending dates) and then gets historical
data from that date forward for all symbols. As I recall, there was
never a problem with getting all data when different symbols had
different ending dates (can occur for a number of reasons) which is
consistent with the earliest last date scenario. If one is
interested, this could easily be checked by creating a small dummy
database containing all data through the current date, delete a
different number of quotes from different symbols, and then run auto
update to see if all symbols are updated properly through the current
date. I have used a number of downloaders through the years and this
is the way they seem to function which makes correcting data for
distributions, etc. relatively easy.
>
> Bill
>
> ----- Original Message -----
> From: "brian_z111" <brian_z111@xxx>
> To: <amibroker@xxxxxxxxxxxxxxx>
> Sent: Saturday, March 15, 2008 10:36 PM
> Subject: [amibroker] Re: quote download?
>
>
> snip
>
> >
> > In this case Tomasz chose to use the end date of the first symbol
as
> > the default start date for auto download i.e. it is an updater
and
> > assumes we start with clean data, have an index as the first
symbol
> > (indexes will always trade) and that we constantly update (keep
> > building the database).
> >
>
> snip
>
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