[Taginfo-dev] tag combinations

[Jochen Topf]

Hi!

By popular request there is now support for counting combinations of tags
(ie key/value, not only keys like before). Example:
http://taginfo.openstreetmap.org/tags/highway=residential#combinations

There is no way to do this efficiently for all 60 Million different tags, so it
is only done for the some tags. Each time taginfo updates its data, it will
create a list of the most interesting keys and tags and uses that list in the
next run to count combinations. Currently interesting keys and tags are those
which appear at least 10000 times minus some handpicked ones. See 
sources/master/interesting_tags.sql for the code. We'll probably need to adapt
this code in the future.

There is currently no way to configure this except changing the SQL (and maybe
the tagstats C++ source). If you try this and need changes for the areas you
run taginfo for, we can see what changes are needed and how to make it more
easily configurable.

Jochen
-- 
Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/  +49-721-388298