[OSM-dev] Block sizes in PBF Format

Jochen Topf jochen at remote.org
Tue Nov 30 09:28:46 GMT 2010

The PBF_Format wiki page states: "The length of a Blob *should* be less than 16
megabytes and *must* be less than 32 megabytes." But forther down it says "I
collect 8k entities to form a PrimitiveBlock, which is serialized into the

So what happens if the 8k entities take up more than 32 megabytes? Thats 4k
per entity, which could be reached with large relations. Well, we need quite
a few of those large relations, but its good to know where the limits of the
format are and they should be clearly documented.

Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/  +49-721-388298

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