Re: [osmosis-dev] postGIS: bbox columns?
Hi, David Carmean wrote: Who/what uses the ways.bbox column? Is there something/somebody that cannot use the linestring gist index, but instead requires an explicit bounding box geometry? Is the bbox column not meant to be a quicker alternative to a full linestring (quicker in importing, not quicker in using)? I.e. you won't have a linestring to base your GIST index on if you use that as intended. Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09 E008°23'33 ___ osmosis-dev mailing list osmosis-dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/osmosis-dev
Re: [osmosis-dev] postGIS: bbox columns?
On Sun, May 23, 2010 at 12:23:27AM +0200, Frederik Ramm wrote: Hi, David Carmean wrote: Who/what uses the ways.bbox column? Is there something/somebody that cannot use the linestring gist index, but instead requires an explicit bounding box geometry? Is the bbox column not meant to be a quicker alternative to a full linestring (quicker in importing, not quicker in using)? I.e. you won't have a linestring to base your GIST index on if you use that as intended. The presence of the gist index on the linestring geometry column is what allows the GIS client I use to link only a small portion of the dataset based on a bounding box I specify; without it, it links the entire table as a drawing layer. The gist index presents a proxy bounding box internally. http://postgis.refractions.net/documentation/manual-1.3/ch03.html#id2570609 As described above, this index can be used to perform a quick first-pass query based on just the table indices (proxy bounding boxes) and present the main query with a pre-filtered set of candidates. I'm just wondering if there's some other application that uses this explicitly-built bbox geometry column (and whether it could be improved by using the index instead). ___ osmosis-dev mailing list osmosis-dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/osmosis-dev
Re: [osmosis-dev] Unable to write String to the store
Hi, Nakor wrote: I was trying to extract a bounding box from planet-100519.osm.bz2 and after one hour or so osmosis stopped running with the error message at the end. You seem to have used one of the --complete-something options. These are real performance killers because they have to cache the full planet in a temp file. Don't use them unless you really have to. If the extract you are making is relatively small, then it can make sense to first do an extract with --clip-incomplete-entities for something that is slightly larger than the bit you want, and then make an excerpt *from that* with the --complete option. I have 175 Gb free on the disk where the planet file resides. Is this not enough? Or is osmosis using another disk for its temporary files? 175 GB is enough because the temp files are gzipped. But it uses /tmp unless you export JAVACMD_OPTIONS=-Djava.io.tmpdir=/my/pretty/little/tempdir before you run it. Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09 E008°23'33 ___ osmosis-dev mailing list osmosis-dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/osmosis-dev
Re: [osmosis-dev] Unable to write String to the store
Frederik, Nakor wrote: I was trying to extract a bounding box from planet-100519.osm.bz2 and after one hour or so osmosis stopped running with the error message at the end. You seem to have used one of the --complete-something options. These are real performance killers because they have to cache the full planet in a temp file. Don't use them unless you really have to. If the extract you are making is relatively small, then it can make sense to first do an extract with --clip-incomplete-entities for something that is slightly larger than the bit you want, and then make an excerpt *from that* with the --complete option. Thanks for the advice. I have 175 Gb free on the disk where the planet file resides. Is this not enough? Or is osmosis using another disk for its temporary files? 175 GB is enough because the temp files are gzipped. But it uses /tmp unless you export JAVACMD_OPTIONS=-Djava.io.tmpdir=/my/pretty/little/tempdir before you run it. The drive with /tmp has only 5Gb left so that might explain the issue. Thanks, N. ___ osmosis-dev mailing list osmosis-dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/osmosis-dev
Re: [osmosis-dev] postGIS: bbox columns?
On Sun, May 23, 2010 at 02:31:13AM +0200, Frederik Ramm wrote: David, [snip] HOWEVER, it takes much longer to import the full linestrings than to just import a bbox in the first place. So if your application, for whatever reason, does not need pre-built geometries, but just an overall idea of where in the world a certain way is, then the bbox builder mechanism in Osmosis allows you to skip linestring generation altogether, saving time and storage space. [snip] Frederik, Thanks for the clarification. Indeed the linestrings are the primary desired feature in my use cases (as will be polygons constructed from the closed ways). Thanks. ___ osmosis-dev mailing list osmosis-dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/osmosis-dev
