[Qgis-developer] Benchmarking QgsExpression against V8
wonder.sk at gmail.com
Tue Jan 10 08:03:24 EST 2012
On Tue, Jan 10, 2012 at 1:00 AM, Pirmin Kalberer <pi_ml at sourcepole.com> wrote:
> -Better performance
> -Possibility for writing custum functions
> -New language for expressions
> -More fat (3.7MB for libv8.so)
Thanks for the benchmark.
I have several things to note:
- it may be interesting to measure the proportion of time necessary
for field calculation / searching. I believe the the evaluation takes
just a small amount of time compared to time required for fetching of
features, therefore a fast engine might not necessarily speed things
- V8 may be aware of the fact that the benchmarked expressions are
constant - and evaluate them during compilation, resulting in much
shorter execution time. It would be good to include a benchmark that
uses variables (column references).
- the engine implements three value logic (true/false/unknown) like in
How would you add support for NULL values in operators?
- Python is another language which could be used for the expressions -
At some point we may support several languages for expressions
dependency looks like a high cost for the exchange of faster
expression evaluation. My impression is that such a state of the art
but not that much for simple expressions.
More information about the Qgis-developer