[OSM-dev] way 7062297, is this new?

Matthias Julius lists at julius-net.net
Mon Oct 13 18:39:31 BST 2008

Julison <julisonbr at gmail.com> writes:

> In what situation would it be necessary use duplicate keys? If there's a
> need, can we reach the same goal without using it? I think duplicated keys
> can lead to database problems (e.g. performance) that can be avoid.

A highway can have multiple refs (A11 could be E22 simultaneously), a
bulding can have a bakery and a butcher's shop in it and there are
certainly other examples where a key can have multiple values.

There has been the recommendation to put all those values in one tag
and delimit them by semicolon.  This is error prone, prevents the
semicolon from being used in the value of tags and probably not
everybody was following that recommendation anyway.

If technical reasons make the use of unique keys necessary I think the
API should sort that out and do the concatenating/splitting and
escaping of those values.

With increasing support for relations across the board, the issue can
be avoided by using one relation for the bakery and one for the
butcher's shop and both referencing the building.


More information about the dev mailing list