[pycsw-devel] CKAN - pycsw integration: last details

[Angelos Tzotsos]

Hi Adria,

Thank you very much for this effort!

Some answers inline:


On 06/26/2013 05:56 PM, Adrià Mercader wrote:
> I have a couple of doubts though:
>
> * Regarding the different backends for geometries, I see that support
> for PostGIS backend will be included in pycsw 1.6.0, which is great.
> What kind of configuration does it require to use a backend or
> another? I didn't find it in the docs, but looking at the code it
> seems that if you want native Postgis you just need to create a geom
> field in the records table (with a different name from wkt_geometry)
> and that's it?
Sorry that I did not find the time to update the master (1.6.0) docs for 
this new feature but the user is not required to do much.
http://pycsw.org/docs/administration.html#setting-up-the-database
The way native PostGIS geometries are handled by pycsw is briefly 
explained here:
https://github.com/geopython/pycsw/issues/124#issuecomment-16693140

Basically, during

pycsw-admin.py -c setup_db -f default.cfg

the administration utility detects if PostGIS is installed in the 
database mentioned in default.cfg. Both PostGIS 1.x and 2.x are detected.
If PostGIS is detected, the script does not create the SFSQL tables (as 
they are already in the db) and creates the metadata table as declared 
in default.cfg. The difference is that it also creates a "wkb_geometry" 
column and a trigger to update it in case "wkt_geometry" field is 
changed. So we have both "wkt_geometry" and native geometry 
("wkb_geometry") columns in the same table to keep compatibility with 
previous versions (or in case PostGIS is disabled for some reason).

Bottom line: no special setup needed. If PostGIS is enabled before 
setting up the pycsw db, the native support is there :)

In case you need to migrate from previous deployment, you will need to 
add the column "wkb_geometry" manually (along with the update trigger) 
and then create a script to fill the geometries from wkt_geometry field. 
We can provide such migration script...

Native column and trigger creation script can be found here:
https://github.com/geopython/pycsw/blob/master/pycsw/admin.py#L257

I promise to update the docs... :)

> Can you give me an example GetRecords request that filters by bbox
> that I can use to test our setup?

This is a demo POST request. You can test using the tester application:
http://geopython.github.io/pycsw-workshop/docs/intro/intro-exercises.html#tester-application

<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
<csw:GetRecords xmlns:csw="http://www.opengis.net/cat/csw/2.0.2" 
xmlns:ogc="http://www.opengis.net/ogc" service="CSW" version="2.0.2" 
resultType="results" startPosition="1" maxRecords="5" 
outputFormat="application/xml" 
outputSchema="http://www.opengis.net/cat/csw/2.0.2" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://www.opengis.net/cat/csw/2.0.2 
http://schemas.opengis.net/csw/2.0.2/CSW-discovery.xsd" 
xmlns:gml="http://www.opengis.net/gml">
     <csw:Query typeNames="csw:Record">
         <csw:ElementSetName>brief</csw:ElementSetName>
         <csw:Constraint version="1.1.0">
             <ogc:Filter>
                 <ogc:BBOX>
<ogc:PropertyName>ows:BoundingBox</ogc:PropertyName>
                     <gml:Envelope>
                         <gml:lowerCorner>47 -5</gml:lowerCorner>
                         <gml:upperCorner>55 20</gml:upperCorner>
                     </gml:Envelope>
                 </ogc:BBOX>
             </ogc:Filter>
         </csw:Constraint>
     </csw:Query>
</csw:GetRecords>


>
> * I seem to remember that there was some talk about offering full text
> support. Has this been implemented and if so what kind of setup does
> it require? (ie is there an index that needs to be created in the DB?

There is an open issue on this. We originally wanted to offer this with 
1.6.0 but we did not get any feedback:
https://github.com/geopython/pycsw/issues/136


>
> Thanks a lot,
>
> Adrià
> _______________________________________________
> pycsw-devel mailing list
> pycsw-devel at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/pycsw-devel
>

Thanks,
Angelos

-- 
Angelos Tzotsos
Remote Sensing Laboratory
National Technical University of Athens
http://users.ntua.gr/tzotsos