2008/12/4 Stefan de Konink <[EMAIL PROTECTED]>: > Marcus Wolschon wrote: >> My reference-implementation for the osmbin-format is nearly >> completely debugged and optimized and I was able to generate >> statistics about the number of ways referenced per nodes, >> distribution of tag-value-length, ... for a much larger sample. >> This time not using the city of Hamburg but the state of >> Baden Wuerttemberg (Germany). >> >> http://wiki.openstreetmap.org/wiki/User:MarcusWolschon/osmbin_draft >> >> I'll try to do all of Germany next. > > Sounds cool :) Do you have the final filesize reduction also calculated? > > Is the structure extendable? (I mean does it allow efficient network > updates)
The file-sizes are stated in the statistics. The Index by ID is optimal if a worldfile or large extract is used and can grow to be larger then the nodes/ways-file for smaller extracts where this does not matter. The nodes.id2 has about the same size as nodes.obm since I was able to reduce the average size of a nodes-record dramatically using the first statistics. The structure is mutable, meaning you can add, modify and remove nodes, ways and attributes at will. The reference-code does that. Thus you can use this as a native on-disk-format for a wide range of applications and directly apply the nightly/ hourly/minutely diffs to it without re-generating the file or downloading more then just the diff. (All code required to do that is already part of LibOSM.) The index can be removed and re-generated or substituted with another kind of index at will. (For example: I have an additional hsqldb-file with an index of all streets, villages, house-numbers and zip-codes indexed by their normalized name for address-searches.) Rules exist to repair a broken file and return it into a consistent state while loosing as little information as possible. I want to publish an automatic repair-tool later (much later). Marcus _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
