Hi,
Marcin Rudowski wrote:
> When I optimized my xml file, I turned off all layers (status=off) and
> enabled by one and measured time of each separately to find which are
> slowest and at which zoom.
There are two useful (for me, at least) Perl scripts (or hacks if you
prefer) in applications/rendering/mapnik/utils in the OpenStreetMap SVN.
Both might require some tweaking to work for you.
"stylecheck.pl" creates a list of SQL queries that will be issued at
various zoom levels. This can help you with a quick indication whether
you might suffer from the problem that Marcin described here, namely a
fairly detailed SQL query that has been pulled to the low zoom levels
("oh, it does a 'where highway is not null' query on my large table
beginning with zoom level 5... not good").
This script only needs your map file as input.
The more complex analyze_posgis_log.pl will load a PostGIS log file
together with your style file and then use the timings from the SQL
queries in the PostGIS log to tell you which layers, at which zoom
levels, need most of the time. It guesses the zoom level from the extent
specified in the SQL query.
As I said, it's all a bit hack-ish but it helped me optimise things a
lot, and I thought I'd share it so maybe it is of use to others.
Bye
Frederik
--
Frederik Ramm ## eMail [email protected] ## N49°00'09" E008°23'33"
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