[OSM-dev] Planet size reduction ideas

spaetz osm at sspaeth.de
Thu Aug 23 08:30:32 BST 2007


Just grepping the planet takes incredibly long nowadays, you can't do anything with it anymore basically, without loading it into a data base.

I very much look forward to the elimination of segments - and the corresponding planet reduction by 40% :-)

1) Additionally we could do some easy stuff to further reduce size. Currently we have 13 post-comma digits in the latitude and longitude. This leads to what - 1 micrometer ? - precision. Is that really needed? We could easily switch to 7 post-comma digits and still remain within centimeter precision if I am not mistaken. Shaving 2 times 6 digits of 14mio nodes, saves us 170MB or so.

2) Also using INT timestamps will be a lot shorter than the 20char time stamp we have now (although that would strictly mean a change of meaning of that field) and save us another 10 bytes or so.
 Do we need the timestamps at all? Are they of interest for anyone, if we could drop them completely, that would save a whole bunch.

spaetz
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