[OSM-dev] RFC: map call to return deleted elements

[Matt Amos]

On Sat, May 23, 2009 at 1:00 AM, Frederik Ramm <frederik at remote.org> wrote:
> SteveC wrote:
>>
>> The SQL and filtering to get all the nodes in a bbox, then see if they
>>  were still actually within the bbox, sort, etc... was non-trivial.
>
> The main difficulty at that time probably was the SQL to return the "latest
> version only" of each object. Matt won't have that problem because even if
> he wants to return deleted objects, he can ignore the history tables - we
> have the deleted objects in the current tables as well. (Plus, you didn't
> have people with a degree in aeronautics. And very few Germans.)

this is OK for the nodes, but we still need to look at the history
tables for the way nodes since the deleted version of the way in
current_way_nodes is empty (ditto for relations). at this point i'm
simply fishing to find out if people think its a good feature. it may
turn out that it is expensive to implement, in which case we'll have
to try something else ;-)

> Someone suggested in the run-up for the 0.6 changeover that we could drop
> the deleted objects from current because he didn't care whether he gets a
> 404 or a 410 return code. It sounded ok at the time but I guess that it this
> were done, returning deleted objects would indeed be a pain.

this is still a good idea, because it would allow us to ensure that no
current way or relation refers to a deleted object by primary key,
rather than doing the check via a query in rails. but, as you say, it
would make implementing this sort of thing a much bigger pain.

cheers,

matt