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 ...
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