[OSM-dev] osm2pgsql slow slim import

Frederik Ramm frederik at remote.org
Thu Dec 1 12:45:44 GMT 2011


On 12/01/11 11:13, "Petr Morávek [Xificurk]" wrote:
> Kai has suggested to me changing configuration of postgresql like this:
> fsync = off
> synchronous_commit = off
> And this worked like a charm

Yes. I wonder if there's a way for osm2pgsql to query postgres about its 
settings and issue a "warning this might take longer" message if someone 
has fsync on?

Also, I was recently told that Postgres 9.1 supports "unlogged tables" 
which, again, break on unexpected termination of the database server but 
are otherwise much faster. In a context where one only uses the slim 
mode tables during data import but does not plan on doing later updates 
- i.e. my new "--drop" mode -, using unlogged tables for the slim mode 
tables could mean a significant performance gain. You cannot have 
spatial indexes on unlogged tables but we don't need that for the slim 
mode tables.

Anyone in the mood for a benchmark?


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