[Qt-interest] Different speed for different-sized lists?

[Konrad Rosenbaum]

On Wednesday 03 November 2010 02:58:55 Anatoly Burakov wrote:
> Basically, i have a "binary format" files (serialized QLists of objects)
> which i use to move data back and forth between several apps, one of
> which uses SQLite as a database engine. I have noticed that when i do
> import of, say, 1000 objects, the speed is about 3-4 objects per second
> (due to complex nature of data added to the database). However, when the
> list is 140'000 objects, the importing speed "magically" goes up to
> 20-30 objects per second. The code always stays the same (basically, a
> for(;;) loop with i < qlist.count() as a condition, so nothing special),
> only the amounts of data are changing.

Something else is changing. While I'm convinced that Qt is "magically nice", 
there is no black magic in it. ;-)

Likely candidates: 
* you send a signal to a different thread to update a progress bar, but the 
frequency changes with the amount (if((count/max)%100 == 0)setProgress(...)).
* you change the frequency of commits to the database


	Konrad
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