Hi Oleg/Everybody,

The latest version of JDB in the package manager is 1.0.3. 

In your wiki page, you wrote that the browser can be loaded this way:
   load 'data/jdb/browser'

I don't know if the problem is with my local addons copy but the browser
script does not exist in the JDB location. I had to manually download
browser.ijs from the wiki page to addons/data/jdb.

Is this true for everyone or I fubar'd my local copy?

r/Alex

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Oleg Kobchenko
Sent: Friday, September 19, 2008 6:01 AM
To: Programming forum
Subject: [Jprogramming] JDB - subsetting result

I published the JDB browser
   http://www.jsoftware.com/jwiki/JDB/Browser

1. Is the method there of transforming Read into boxed
table optimal for using with Grid?

2. I think it would be good for such visual applications,
browsing etc to have the ability to subset the result.
Given a query result, but without returning it in full,
there are such features of interest:

 * provide total number of rows in the result
 * return a contiguous subset given rowstart and rowcount
 * return every i-th row
 * return rows given arbitrary indices

The first two are for pagination and virtual Grid.

The last two are good for preview-detail graphical
applications such as lens-and-chart
  http://www.jsoftware.com/jwiki/Addons/media/wav#viewer

QDB solves this providing pseudo-column i as the result 
row index, so you can say "where i>20,i<40" etc.

In JDB it could be a left argument to Read-family verbs,
or separate verb(s). The idea is that there is Readr index,
on which this subsetting can operate, before it is embodied
with select columns.



> From: Chris Burke <[EMAIL PROTECTED]>
> 
> The new JDB addon is an efficient relational database written in J,
see:
> http://www.jsoftware.com/jwiki/JDB .
> 
> ...


      
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