[OSM-dev] production site disk use question

Frederik Ramm frederik at remote.org
Tue Jan 1 20:37:45 GMT 2013


On 01.01.2013 18:52, Jeff Meyer wrote:
> So, it seems like I'll need both the history & the
> current tables. In a non-history planet.osm extract,

Yes, if you want any kind of write access *and* read access through the 
API (instead of reading with specialised queries) then I guess you'll 
need both. The current tables always duplicate stuff that is in the 
history tables already, and in theory you could always make queries of 
the kind "where version=(select max(version) ...)" against the history 
tables to get the same you find in the current tables, but that would be 
too expensive.

> should those tables
> be the same in an initial import?

Yes, with the exception that foreign keys contain the version number in 
the history tables but not in the current tables (since the current 
tables only contain ONE way ID #1234, the current_way_tags can afford to 
reference only the way ID, whereas in the history table it must 
reference way ID and version).


Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"

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