[OSM-dev] [OSM-talk] Is there some lag in the backend data?

[Andy Allan]

On 24 July 2013 04:22, Ian Dees <ian.dees at gmail.com> wrote:

> iD clears out its internal representation of OSM data when a user's Save is
> successful and then re-requests the area in the viewport immediately. The
> replication delay for a read-only API needs to be less than 2 or 3 seconds
> in this scenario.

The physics of this starts to make it impossible.

Perhaps it's better to explore a sort of inverse "if-modified-since"
header. Clients would be able to request an initial bounding box
without any particular constraint, and assume that it's within a few
minutes of being up-to-date. But after making an upload they could
request a bounding box with "only if replicated since: <timestamp>".
The server can then indicate that it can't fulfill the request and the
client retries later, or the server could proxy the request to the
main API, or something else.

Cheers,
Andy

P.S. This is why I'm focussed on db-level replication for scaling API
read requests, but we should work this through and be able to choose
between alternatives!