Hello everyone,
I have attached a 2nd spreadsheet to issue 89976, please see:
http://www.openoffice.org/issues/show_bug.cgi?id=89976
The column C is unfilled (except for the first 3 cells). Everyone can
now fill as many cells in the C-column as he wishes. Filling the first
1,000 is likely to be computed in real-time, filling the first 10,000
will take some time on slower computers (like mine), filling 30,000
cells will likely take quite long even on a fast PC, and filling ALL
65,535 cells will take some ages. ;-)
I decided to recreate the spreadsheet, because, IF Calc uses a naive
algorithm to update downstream cells, updating them ALL will need to
perform 6.6 million sort operations on 65,535 elements (column C). That
will take a huge amount of time and will basically render the original
spreadsheet unusable. [I am actually unaware on Calc's internal
workings, BUT a naive algorithm seems likely.]
One has now greater flexibility in choosing how many elements column C
will contain.
Open the 2nd spreadsheet, select cell C3 and fill down as many cells as
you wish. I would recommend starting with 1,000 -10,000 cells and moving
slowly towards more cells. The process is likely O(n^2) or worse, so
every slight increase will have a dramatic effect.
By the way, I noticed a BUG in OOo-dev 3.0 beta m14:
- you cannot have $B$1:B1, it will automatically convert to $B$1:$B$1,
BUT $B$1:B2 is still possible (I depend on this functionality)
Please also note, that Calc takes a long time to update formulas, BUT
somehow I feel that most time is wasted on unknown processes: e.g. Calc
will display "Adapt row height" and this operation will take on my
computer as much as (or more than) the proper sort-operation.
I have written additional comments on the naive algorithm vs more
advanced algorithms in the spreadsheet document. Please read carefully.
I hope that this spreadsheet will make it a good test-case to test
future performance.
Sincerely,
Leonard
Leonard Mada wrote:
Dear Caolan,
I have attached a test-spreadsheet to issue 89976.
[http://www.openoffice.org/issues/show_bug.cgi?id=89976]
Please have a look.
It took me over one hour to generate the spreadsheet (basically
waiting for over one hour to fill in column C).
Now that I closed the spreadsheet, it seems I need another hour to
re-open the spreadsheet (due to the recalculations, and I do NOT have
the patience to wait for it). The spreadsheet is not finished, but
unless I have a lot of time to open and work with it, I do not think I
will try it again.
Have fun in debugging Calc.
Sincerely,
Leonard
Caolan McNamara wrote:
Does the calc team have anything like a performance testcase
spreadsheet ? Something along the lines of a computational performance
test as opposed to something IO bound.
C.
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