[OSM-dev] Osmosis - sorted streams

Karl Newman siliconfiend at gmail.com
Fri Dec 21 20:02:23 GMT 2007


On Dec 21, 2007 8:15 AM, Frederik Ramm <frederik at remote.org> wrote:
> Hi,
>
>   two questions regarding sorted streams in Osmosis:
>
> 1. does --m/--mc depend on the input streams being sorted? It is not
> documented as doing so but any pipelining algorithm I can think of
> would essentially require sorted input.
>
> 2. provided all inputs are sorted, which Osmosis tasks will create
> *unsorted* output? --bp/--bb with completeWays/completeRelations
> perhaps? Any others?

1. It's not stated explicitly but that does seem to be required. It's
doing sequential comparisons between the two inputs, which would be
meaningless without both inputs being sorted.

2. The area filtering task with completeWays and completeRelations
should maintain the order as presented to it (assuming all nodes
first, then all ways, then all relations); it was a consideration when
I wrote it, anyway. I don't know about the other tasks, but from what
I've seen my impression is that the order is maintained.

Karl




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