Hi Peter & Jochen, > I encountered shrinkage of around 1-2% of the overall block size while > comparing the intermediate string ids with the sorted ones.
sounds plausible. Sorting the strings might not be worth the effort if circumstances allow you to increase block size. I just ran a comparison (File germany.pbf had been downloaded from Geofabrik at November 22): $ time ./osmconvert germany.pbf -o=germany_oc.pbf real 2m32.438s $ ls -l germany* -rw------- 1 pt pt 1089521558 2011-12-13 18:53 germany_oc.pbf -rw-r--r-- 1 pt pt 1150359237 2011-11-22 04:02 germany.pbf Result: 8000 objects/block (download file) -> n objects/block, but 30..31 MB/block (osmconvert) saves about 5% file size. Markus -------- Original-Nachricht -------- > Datum: Tue, 13 Dec 2011 16:39:00 +0100 > Von: "Peter Körner" <[email protected]> > An: [email protected] > Betreff: Re: [OSM-dev] Writing PBF > Am 13.12.2011 15:04, schrieb Jochen Topf: > > Has anybody any data on how much smaller the files get with sorted vs. > unsorted > > string table? Sorting the string table means there is a lot more work > and a lot > > more main memory needed for the PBF writer. > I encountered shrinkage of around 1-2% of the overall block size while > comparing the intermediate string ids with the sorted ones. > > Peter > > _______________________________________________ > dev mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/dev _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
