[OSM-dev] Simpler binary OSM formats

Andrew Byrd andrew at fastmail.net
Mon Feb 8 10:37:51 UTC 2016


> On 08 Feb 2016, at 10:57, Andrew Byrd <andrew at fastmail.net> wrote:
> To me, it seems much more advantageous to provide a table of file offsets stating where each entity type begins. I have already considered adding this to vex after the basic format is established (like author metadata and map layers). It seems appropriate to place such a table at the end of the vex data, because this allows the writer to produce output as a stream (no backward seeks) and a reader can only make effective use of this table if it’s buffering the data and able to seek within the file.

On second thought, if the table is to be placed at the end of the file/stream the writer would not even necessarily need to store it because the reader can easily construct an equivalent table as it receives the data (or the first time it scans over the file).

-Andrew


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