[OSM-dev] tiles at home disk usage

Martijn van Oosterhout kleptog at gmail.com
Wed May 2 19:40:03 BST 2007


On 5/2/07, Robert Hart <bathterror at gmail.com> wrote:
> something like:
> First part of file is an index to find the data for each line of
> latitude (i.e. a table of pointers/offsets in the file)
> The second part is a series of pairs (value, repeat count), which
> describe what you'd find as you work along that line of latitude from
> end to end. A zero repeat count could indicating end of a row, but you
> shouldn't need that.

If it were a read-only structure I'd agree. The problem is that you're
going to get updates regularly, so you have to uncompact a line,
change the relevent bits, then recompact it. If it doesn't fit
anymore, what then?

You can build all sort of dynamic structures, btree, etc, but I don't
have the stomach to debug them. I'd really prefer the 4 lines of code
method that I can see works :)

If you rewrite the file every few minutes I think you lose most of the
caching advantage. But this is just supposition. If you want to try
implementing it, i'd say it's worth a shot.

Have a nice day,
-- 
Martijn van Oosterhout <kleptog at gmail.com> http://svana.org/kleptog/




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