[OSGeo-UK] Astun Technology OSMM Loader In Practice
Tim.Martin at ordnancesurvey.co.uk
Fri Aug 26 07:52:48 EDT 2011
Matt Walker asked if I would document my use of the OSMM Loader, so here
I tested both the initial (direct PostGIS loading using INSERT) and the
significantly quicker PGDump version on national coverage OSMM.
I used the non-geo chunks, as I didn't want to have to post process the
database tables to remove identical features. Matt has this down as a
future improvement and I would second that along with COU as being
Details as follows
1) Step 1 was to use the Astun loader to create the SQL Dump/COPY files.
For this I used a High-CPU Windows 64 Bit with Python 2.5 and GDAL 1.8
installed via the OSGeo4W installer.
Using Non-Geo chunks of OSMM there are 1297 files equating to 35.9GB, I
used 6 threads (the computer had 8 cores) to process 216 files/6Gb each
and this took 15 hours and outputted 215Gb of SQL files, one for each
2) Step 2 Data Loading
I used the inbuilt PSQL loader and run 2 threads on a Large Windows
Amazon Instance to load the data in PostGIS. Only 2 threads could be
used as the Large instances only have 2 cores - although it was only
using 30-40% of total CPU, so could potentially up this to 4 threads.
The load took 13-14 hours
3) Running the spatial indexes
I amended the config of PostGIS and upped the maintenance memory to 1Gb.
This helped created the spatial indexes in less than 10 hours compared
to the original 17 hours with default PostGIS
So SQL creation + data load + indexes = 40 hours.
I guess for many people it will be the fear of using a commandline tool
(people love a good GUI) and the fact they do not have access to these
I have been very impressed though and would like to thank Matt for his
Tim Martin Msc Bsc(Hons)
Web Services Consultant and INSPIRE Technical Business Development
Mobile: +44 (0) 7917 550 225
www.ordnancesurvey.co.uk | Tim.Martin at ordnancesurvey.co.uk
<mailto:Tim.Martin at ordnancesurvey.co.uk>
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