[OSM-dev] [API] Suggestion: Baselines

Chris Browet cbro at semperpax.com
Tue May 26 13:47:44 BST 2009

2009/5/26 Stefan de Konink <stefan at konink.de>

> Chris Browet wrote:
>>    If you just want to materialise the entire database at a certain
>>    interval, don't you think this will grow very fast?
>> I don't know. A baseline would only consist of a list of all objects id
>> with their associated version number at a certain point in time, not the
>> actual objects...
> Think of a way X; it consist of n nodes. If you take the this way at
> changeset Y, you would still have to find all nodes positions at time(Y).

Sure, but as we'd take a version snapshot of all objects anyway, the X way
will still be only say 8 bytes for the id and n (don't know the definaition
for versions, let's assume 4) bytes for the version. That is 12 bytes per
object * 360.000.000 is ~4.5Gb.

Assuming daily, one year rotating, online baselines, that makes 1.5 Tb, i.e.
2 big disks (with overhead), i.e. 200€.

Not that expensive IMHO...
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