[OSM-dev] Optimal free compression algorithm for OSM XML data
nick at nickhill.co.uk
Thu May 10 09:25:42 BST 2007
After a brief discussion at the developers conference in Oxford regarding
compression algorithms for planet.osm, I decided to perform a series of tests
using different algorithms available in free software.
I chose the latest planet-070509.osm.
The following algorithms:
I determined CPU time to compress, uncompress and compressed file size:
Time Time File Size
pack Unpack Mebibytes
bzip2 7144 347 246
7-zip 4436 114 218.6
gzip -6 186 36 345
gzip -9 474 36 322
zip Failed - file size too large
From the above, the user will likely have the best experience using 7-zip.
Smallest download size, whilst costing only 1/3rd of bzip2 to unpack. For OSM,
7-zip is less costly, taking only 62% of the time it takes to compress the
gzip unpacked much faster than my hard drive could write, 7zip was a little
faster than my hard drive.
These tests were performed with an AMD Athlon 2200+ 32 bit running at a clock
speed of 1498Mhz from the year 2002.
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