[Monetdb-developers] are BAT ids are fixed

Stefan Manegold Stefan.Manegold at cwi.nl
Mon Mar 22 20:23:14 CET 2010


On Mon, Mar 22, 2010 at 11:45:21PM +0530, anshul gangwar wrote:
> hello,
> 
>     I want to know whether BAT ids are fixed.

BAT ids are fixed for the life-time of a BAT, i.e., on creation, a BAT is
assigned an ID, which is keeps unchanged and exclusively until the BAT is
destroyed, again.

> If fixed then what does that
> BAT_select_(b=tmpr_2322): BATslice(v=tmp_2403, low=0, high=1)
> means?

This means that a range (or point) selection on a tail-sorted BAT is
executed by looking up the positions of the lower and higher bound of the
range (using binary search) and then getting the complete result as a
positional slice of the BAT between these two positions.

See MonetDB/src/gdk/gdk_batop.(mx|c) for details.

Stefan

ps: Please note that the information you get about the runtime
    algorithm/implementaion choice (using --debug=$[2*1024*1204]) is mainly
    meant for core developers of MonetDB when analysing and debugging the
    system; hence, it is (a) not guaranteed to be complete and (b) makes
    only sense in case you know and understand the code in MonetDB/src/gdk/
    quite well ...
 
>       The INTERNET now has a personality. YOURS! See your Yahoo! Homepage. http://in.yahoo.com/

> ------------------------------------------------------------------------------
> Download Intel® Parallel Studio Eval
> Try the new software tools for yourself. Speed compiling, find bugs
> proactively, and fine-tune applications for parallel performance.
> See why Intel Parallel Studio got high marks during beta.
> http://p.sf.net/sfu/intel-sw-dev

> _______________________________________________
> Monetdb-developers mailing list
> Monetdb-developers at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/monetdb-developers


-- 
| Dr. Stefan Manegold | mailto:Stefan.Manegold at cwi.nl |
| CWI,  P.O.Box 94079 | http://www.cwi.nl/~manegold/  |
| 1090 GB Amsterdam   | Tel.: +31 (20) 592-4212       |
| The Netherlands     | Fax : +31 (20) 592-4199       |




More information about the developers-list mailing list