[no subject]

Tutorial: Understanding AmiBroker database concepts
Background
A typical Windows application, for example, Paint, works with a SINGLE file. 
You just open and save that single file (.BMP in Paint, or .DOC in MS WORD), and 
that file holds all the necessary information.
AmiBroker is a more complex piece of software. It uses huge amounts of data 
(all quotes from different tickers, hand drawn studies, assignments to groups, 
markets, watch lists, favorites, industries, sectors, etc.), so it must manage 
multiple files.
It would actually be possible to save all this information in a single file, 
but it would be (a) huge, and (b) slow to update selectively. So AmiBroker uses 
multiple files for storing all the data. There are a lot of files associated 
with any database. The files for a particular database are stored in a directory 
(and its subdirectories) specific to that database. In AmiBroker documentation, 
such a directory is referred to either as a "database directory" (versions 3.9 
or later) or as a "workspace directory" (earlier AmiBroker versions).
When you install AmiBroker for the first time, a default database directory 
is created, called 'data', in the AmiBroker directory. This database directory 
contains a sample Dow Jones Industrial Average database.

In AmiBroker database menu and dialog selections, you are choosing or 
creating a database directory, not an individual file.
AmiBroker database structure
A database (or a workspace) is a directory that holds a set of binary files, 
which are stored in 0-9, a-z, '_' subdirectories. Those binary files hold 
quotes, stock information, your studies (trend lines, Fibonacci stuff). Each 
symbol's information is stored separately in the file with the name of the 
ticker symbol located in the subdirectory corresponding to the first character 
of the symbol, so IBM quotation data/studies are stored in the 'IBM' file 
located in the 'I' subdirectory.
The default database for AB is the 'data' directory. It contains DJIA sample 
data. You may create additional databases in other directories via the 
File->'New database' menu.
In addition to these subdirectories and files, two additional files are also 
created by AmiBroker: broker.workspace and broker.master. The first is usedto 
store category names and information about advancing/declining/unchanged issues. 
The latter stores the table of all symbols that is used for quick loading of the 
database. These two files are located in the root directory of each database, 
the 'data' directory, by default.
In almost all cases, you should NOT touch files in an AmiBroker database, 
as the program manages them automatically, and no user intervention is 
required.

What about the external data?
AmiBroker 3.9 has the ability to read quotes DIRECTLY from an external data 
source. Currently, AmiBroker can read directly from Quotes Plus (QP2), TC2000 
(TC2K) and Metastock (MS) databases. This is achieved by means of data plug-ins 
that AmiBroker uses to read the data from an external data source. When a user 
decides that she/he wants to use an external database - AmiBroker - insteadof 
reading the quotes from its own database - just asks the plug-in for quotesfor 
any given symbol. The plug-in reads the external database and feeds the data to 
AmiBroker. The whole process is shown in the picture below:
<IMG height=276 
src="" 
width=449>
As you can see, data plug-ins provide read-only access to the quotes 
in the external database. This means that your external data sources are never 
modified by AmiBroker. Changes or additions that you make to data and charts 
(like hand drawn studies, assignments to categories, etc.) are always savedin 
AmiBroker's own database. So AmiBroker still uses its own database (to save 
changes, as a cache to speed up access, and for other tasks), even when using an 
external data source.
The Data source switch represented in the graphic above can be set by the 
user to access various external databases. External data sources are selected by 
going to the File->'Database settings' dialog, shown below: 

<IMG height=431 
src="" 
width=387>
You may also choose to store the quotes retrieved from the external source to 
AmiBroker's own database for faster retrieval in subsequent accesses. If you 
want to do this, you should switch the 'Local data storage' setting to 
'Enabled'.
Note: Similar settings can be found in the Tools->Preferences 'Data' tab, 
but these are only defaults used when creating new databases. 
File->Database Settings configurations always take precedence over those 
done in Preferences -- EXCEPT in the following cases: If you choose the 
'Default' entry in the Data Source drop down list (shown above), or the 
'Default' radio button for Local Data Storage (also shown above), AmiBrokerwill 
use your Preferences settings for those items.

-----Original Message-----From: miked33 [<A 
href="">mailto:miked@xxxx]Sent: 
Thursday, July 18, 2002 4:17 PMTo: amibroker@xxxxxxxxxxxxxxxSubject: 
[amibroker] Quotes Plus ProblemsI have just switched from Yahooto 
Quotes Plus for data.  I amdownloading Stocks and Indexes.  Is 
this what others are downloading?This is over 5000 stocks and is taking 
forever to do a 1 day update. Matter of fact sometimes in runs forever 
and I F12 it.  It alsoappears to have slowed Amibroker down quite a 
bit.  What are othersdownloading and is their a way to optimize the 
database?------------------------ Yahoo! Groups Sponsor 
---------------------~-->Will You Find True Love?Will You Meet the 
One?Free Love Reading by phone!<A target=_blank 
href="">http://us.click.yahoo.com/ps3dMC/R_ZEAA/Ey.GAA/GHeqlB/TM---------------------------------------------------------------------~->Your 
use of Yahoo! Groups is subject to <A target=_blank 
href="">http://docs.yahoo.com/info/terms/