[Paraview] VALUES or THRESHOLDS selections

[Jean Favre]

I have a filter doing cell selection from an array of material ids. The
usage pattern is to select a single material id, i.e. a single number.

To debug and check my filter's output, I ran the same with the Selection
Inspector. However, ParaView only enables THRESHOLDS selection in the
Selection Inspector. Is there a reason the alternative, selection by
VALUES (described in a very good article on page 3 of The Source, April
2009) is not available?

I am running into a problem with my filter's CELL selection. If I use
THRESHOLDS, and set the SelectionList to an array of size 2 (both values
being equal since I want to select a single material ID), the filter
executes really fast and gives the correct result. If instead, I use
VALUES, and set the SelectionList to an array of size 1, execution is
extremely slow. I measured
2.4 secs for 27,000 cells
253 secs for 270,000 cells
and a seg fault for 2,700,000 cells.

Every time I tried to stop execution, I am inside the QuickSort class.
Are there issues with that? Isn't the complexity of the sorting supposed
to be n*log(n)? that is not what I see when I get execution times from
2.4 to 253 secs when going from 27000 to 270000 cells.

Note that I get the correct results with VALUE-selection (even though
very slowly), identical to the selection by THRESHOLDS (except for the
last case with the seg fault)

any experience from other users?

Jean--
Swiss National Supercomputer Center