[OSM-dev] New OSM binary fileformat implementation.
scrosby06 at gmail.com
Wed Apr 28 20:07:46 BST 2010
> I have a quick question: does the format support inserting data to an
> existing file? Or is it just some binary serialization?
The format is a binary serialization design and does not support
random-access read and write semantics. For that a database is probably more
However, some changes can be done to a file relatively cheaply. Data can be
trivially appended. Rewriting a file could be fairly cheap as each fileblock
is independently decodable and contains only 8,000 OSM entities. A fileblock
can be copied from an input to an output without decompressing or parsing
it. Metadata in the block header could be used to find out which fileblocks
can be copied unchanged, or used to filter out unwanted blocks.
> Now we just need the dump tool for the database to create some planet dump
> file in your format.
If osmosis is used as the dump tool, I believe a --write-bin should suffice
to make a planet dump. The code just ties into the existing Source/Sink
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