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Fixed #13315, #13430 -- Recreated django.contrib.gis.db.backend module with SpatialBackend alias and added Adaptor alias for backwards-compatibility purposes; added GeoDjango 1.2 backwards-incompatibility documentation and release notes; added a section in the docs about how MySQL is a crippled spatial database; updated versions in install docs.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@13097 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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Justin Bronn
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12 changed files with 226 additions and 26 deletions
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@ -23,13 +23,16 @@ its functionality into full-fledged spatial database backends:
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* :mod:`django.contrib.gis.db.backends.oracle`
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* :mod:`django.contrib.gis.db.backends.spatialite`
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Backwards-Compatibility
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-----------------------
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Database Settings Backwards-Compatibility
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-----------------------------------------
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For those using the old database settings (e.g., the ``DATABASE_*`` settings)
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Django 1.2 will automatically use the appropriate spatial backend as long
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as :mod:`django.contrib.gis` is in your :setting:`INSTALLED_APPS`. For
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example, if you have the following in your settings::
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In :ref:`Django 1.2 <releases-1.2>`, the way
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to :ref:`specify databases <specifying-databases>` in your settings was changed.
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The old database settings format (e.g., the ``DATABASE_*`` settings)
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is backwards compatible with GeoDjango, and will automatically use the
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appropriate spatial backend as long as :mod:`django.contrib.gis` is in
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your :setting:`INSTALLED_APPS`. For example, if you have the following in
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your settings::
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DATABASE_ENGINE='postgresql_psycopg2'
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@ -41,9 +44,37 @@ example, if you have the following in your settings::
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...
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)
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Then, :mod:`django.contrib.gis.db.backends.postgis` will automatically be used as your
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Then, :mod:`django.contrib.gis.db.backends.postgis` is automatically used as your
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spatial backend.
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.. _mysql-spatial-limitations:
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MySQL Spatial Limitations
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-------------------------
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MySQL's spatial extensions only support bounding box operations
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(what MySQL calls minimum bounding rectangles, or MBR). Specifically,
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`MySQL does not conform to the OGC standard <http://dev.mysql.com/doc/refman/5.1/en/functions-that-test-spatial-relationships-between-geometries.html>`_:
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Currently, MySQL does not implement these functions
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[``Contains``, ``Crosses``, ``Disjoint``, ``Intersects``, ``Overlaps``,
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``Touches``, ``Within``]
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according to the specification. Those that are implemented return
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the same result as the corresponding MBR-based functions.
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In other words, while spatial lookups such as :lookup:`contains <gis-contains>`
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are available in GeoDjango when using MySQL, the results returned are really
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equivalent to what would be returned when using :lookup:`bbcontains`
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on a different spatial backend.
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.. warning::
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True spatial indexes (R-trees) are only supported with
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MyISAM tables on MySQL. [#fnmysqlidx]_ In other words, when using
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MySQL spatial extensions you have to choose between fast spatial
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lookups and the integrity of your data -- MyISAM tables do
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not support transactions or foreign key constraints.
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Creating and Saving Geographic Models
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=====================================
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Here is an example of how to create a geometry object (assuming the ``Zipcode``
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@ -307,4 +338,12 @@ Method PostGIS Oracle SpatiaLite
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.. [#fngeojson] *See* Howard Butler, Martin Daly, Allan Doyle, Tim Schaub, & Christopher Schmidt, `The GeoJSON Format Specification <http://geojson.org/geojson-spec.html>`_, Revision 1.0 (June 16, 2008).
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.. [#fndistsphere14] *See* `PostGIS 1.4 documentation <http://postgis.refractions.net/documentation/manual-1.4/ST_Distance_Sphere.html>`_ on ``ST_distance_sphere``.
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.. [#fndistsphere15] *See* `PostGIS 1.5 documentation <http://postgis.refractions.net/documentation/manual-1.5/ST_Distance_Sphere.html>`_ on ``ST_distance_sphere``.
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.. [#] MySQL only supports bounding box operations (known as minimum bounding rectangles, or MBR, in MySQL). Thus, spatial lookups such as :lookup:`contains <gis-contains>` are really equivalent to :lookup:`bbcontains`.
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.. [#fnmysqlidx] *See* `Creating Spatial Indexes <http://dev.mysql.com/doc/refman/5.1/en/creating-spatial-indexes.html>`_
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in the MySQL 5.1 Reference Manual:
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For MyISAM tables, ``SPATIAL INDEX`` creates an R-tree index. For storage
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engines that support nonspatial indexing of spatial columns, the engine
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creates a B-tree index. A B-tree index on spatial values will be useful
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for exact-value lookups, but not for range scans.
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.. [#] Refer :ref:`mysql-spatial-limitations` section for more details.
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@ -150,13 +150,13 @@ directly from Python using ctypes.
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First, download GEOS 3.2 from the refractions website and untar the source
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archive::
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$ wget http://download.osgeo.org/geos/geos-3.2.1.tar.bz2
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$ tar xjf geos-3.2.1.tar.bz2
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$ wget http://download.osgeo.org/geos/geos-3.2.2.tar.bz2
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$ tar xjf geos-3.2.2.tar.bz2
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Next, change into the directory where GEOS was unpacked, run the configure
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script, compile, and install::
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$ cd geos-3.2.1
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$ cd geos-3.2.2
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$ ./configure
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$ make
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$ sudo make install
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@ -273,9 +273,9 @@ supports :ref:`GDAL's vector data <ref-gdal>` capabilities [#]_.
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First download the latest GDAL release version and untar the archive::
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$ wget http://download.osgeo.org/gdal/gdal-1.7.1.tar.gz
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$ tar xzf gdal-1.7.1.tar.gz
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$ cd gdal-1.7.1
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$ wget http://download.osgeo.org/gdal/gdal-1.7.2.tar.gz
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$ tar xzf gdal-1.7.2.tar.gz
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$ cd gdal-1.7.2
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Configure, make and install::
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@ -516,9 +516,9 @@ user. For example, you can use the following to become the ``postgres`` user::
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The location *and* name of the PostGIS SQL files (e.g., from
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``POSTGIS_SQL_PATH`` below) depends on the version of PostGIS.
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PostGIS versions 1.3 and below use ``<sharedir>/contrib/lwpostgis.sql``, whereas
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versions 1.4 and 1.5 use ``<sharedir>/contrib/postgis-1.4/postgis.sql`` and
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``<sharedir>/contrib/postgis-1.5/postgis.sql``, respectively.
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PostGIS versions 1.3 and below use ``<pg_sharedir>/contrib/lwpostgis.sql``;
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whereas version 1.4 uses ``<sharedir>/contrib/postgis.sql`` and
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version 1.5 uses ``<sharedir>/contrib/postgis-1.5/postgis.sql``.
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The example below assumes PostGIS 1.5, thus you may need to modify
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``POSTGIS_SQL_PATH`` and the name of the SQL file for the specific
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