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OCCI

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Mapnik's PluginArchitecture supports the use of different input formats.

One such plugin supports the Oracle Spatial (Oracle Spatial) extension to the popular ORACLE database.

At the current time, only oracle version 10.2.0.x (10g) and 11.2.0.x (11g) are supported

Installation (On Linux)

Install the Oracle Instant Client package on your system.

Make sure you define where the includes and library files resides in config.py:

OCCI_INCLUDES='/usr/lib/oracle/11.2.0.2/client/include'
OCCI_LIBS='/usr/lib/oracle/11.2.0.2/client/lib'

Make sure that running python scons/scons.py DEBUG=y shows the following line

Checking for C++ library ociei... yes

To check if the occi plugin built and was installed correctly, try the usual Python from mapnik import * on a DEBUG=y build, and look for the following debug line

registered datasource : occi

Troubleshooting

double free or corruption error (oracle 10g only)

If you have problems when running the oracle input plugin and get this when accessing geometries:

*** glibc detected *** double free or corruption (!prev): 0x08c52568 ***

go to http://www.oracle.com/technology/tech/oci/occi/occidownloads.html and download the package 10.2.0.3.0 and overwrite the libraries in your oracle instantclient install path.

Look here for references on the problem.

libtool error: libstdc++.so.5

libtool error: libstdc++.so.5: cannot open shared object file: No such file or directory

Make sure you have compat-libstdc++-33 installed.

Parameters

parameter value description default
host string name of the oracle host
user string username to use for connecting
password string user password to use for connecting
table string name of the table to fetch, this can be a sub-query
geometry_field string name of the geometry field, in case you have more than one in a single table GEOLOC
extent string maxextent of the geometries determined by querying the oracle metadata for the table
row_limit integer max number of rows to return when querying data, 0 means no limit 0
row_prefetch integer number of rows to prefetch from the query before converting them to mapnik features (this allows to finetune the balance between transfer time and conversion time) 1000
initial_size integer initial size of the stateless connection pool 1
max_size integer max size of the stateless connection pool 10
use_spatial_index boolean choose wheter to use the oracle spatial index when fetching data true
multiple_geometries boolean wheter to use multiple different objects or a single one when dealing with multi-objects (this is mainly related to how the label are used in the map, one label for a multi-polygon or one label for each polygon of a multi-polygon) false
encoding string internal file encoding utf-8

Usage

Python

Instantiate a datasource like:

    lyr = Layer('Geometry from Oracle Spatial')
    lyr.datasource = OCCI(host='localhost',user='scott',password='tiger',table='worldborders',geometry_field='geom')

XML

If you are using XML mapfiles to style your data, then using a Oracle datasource looks like:

      <Layer name="countries" status="on" srs="+proj=latlong +datum=WGS84">
        <StyleName>countries_style_label</StyleName>
        <Datasource>
          <Parameter name="type">occi</Parameter>
          <Parameter name="host">localhost</Parameter>
          <Parameter name="user">scott</Parameter>      
          <Parameter name="password">tiger</Parameter>
          <Parameter name="table">worldborders</Parameter>
          <Parameter name="geometry_field">geom</Parameter>
          <Parameter name="extent">-180,-90,180,89.99</Parameter>
        </Datasource>
      </Layer>

C++

Plugin datasource initialization example code can be found on PluginArchitecture.

A OCCI datasource may be created as follows:

    {
        parameters p;
        p["type"]="occi";
        p["host"]=oracle_server_hostname;
        p["username"]=oracle_server_username;
        p["password"]=oracle_server_password;
        p["table"]="worldborders";
        p["geometry_field"]="geom";
        p["extent"]="2309554.99818767,5024797.73763923,2318414.90507308,5040447.94690007"; // optional

        Layer lyr("World Borders");
        lyr.set_datasource(datasource_cache::instance()->create(p));
        lyr.add_style("worldborders");
        m.addLayer(lyr);
    }
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