[postgis-users] strange benchmark results

[Andreas Brandl]

Hi Mark,

> > I would really appreciate any insight on this behaviour. Next I'm
> going to run the benchmark on a linux OS.
>
> As a quick test, I would suggest upgrading to the new Windows
> StackBuilder packages since they contain GEOS 3.2.0 which had a number
> of memory leaks fixed and see if you see the same behaviour on Test 1,
> i.e. slowly increasing query times.

This one is in the 'queue'.

> I'd also be interested to see your results of just Test 1 on a Linux
> OS too to see whether it is an OS specific issue that you are seeing.

I executed the benchmark on Debian Lenny, 32-bit. Same machine, same config, same data, same benchmark. Quite astonishing results [1].

Not only the effect is another one (please see graphs), the queries are much faster on Debian than on WinXP. But this only concerns those queries shown here, other queries behave 'normal' (i.e. some faster, some slower, no 'increasing effect'). I additionally validated and compared the query results, they are the same.

I noticed the different PROJ Versions (postgis at winxp having Rel. 4.6.1, postgis at debian having Rel. 4.7.1) but as I am not using any projection (default SRID -1) I suppose this does not matter here. Another difference is that I used StackBuilder on Windows and compiled everything from source on debian.

Is this going to be a serious issue? May I provide further information or assist you in some other way?

Best regards,
Andreas

[1] http://students.fim.uni-passau.de/~brandlan/ba/benchmark/postgis-02/timeline_postgres_index.html