PostGIS - Geographic Information Systems Extensions to PostgreSQL
~~~~~~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

VERSION: 1.4.0 (TBC)

MORE INFORMATION: http://postgis.refractions.net

This distribution contains a module which implements GIS simple 
features, ties the features to rtree indexing, and provides some 
spatial functions for accessing and analyzing geographic data.

Directory structure:

  ./            Build scripts and install directions.
  ./liblwgeom   LWGEOM access library.
  ./lwgeom      PostGIS library source code.
  ./java/ejb    EJB Java support
  ./java/jdbc   Extensions to the PostgreSQL JDBC drivers to support
                the GIS objects. 
  ./java/pljava PostgreSQL PL/Java spatial object support
  ./doc         PostGIS Documentation 
  ./loader      A program to convert ESRI Shape files into SQL text
                suitable for uploading into a PostGIS/PostgreSQL database
                and a program for converting PostGIS spatial tables into
                Shape files.
  ./utils       Utility scripts for PostGIS (upgrade, profiling, ...)
  ./extras      Various pieces that didn't belong to mainstream
	        (package management specfiles, WFS_locks, sample wkb parser)
  ./regress     Regression tests
	        

REQUIREMENTS
------------

PostGIS is compatible with PostgreSQL 8.1 and above.

You *must* have full PostgreSQL - including server headers - installed
for this to work. 

SEE THE NOTE ON GEOS SUPPORT BELOW FOR SPECIAL COMPILATION INSTRUCTIONS

* PROJ4 SUPPORT (Required): 

  The Proj4 reprojection library is required if you want to use the 
  transform() function to reproject features within the database.

    http://trac.osgeo.org/proj/

* SPATIAL PREDICATE / GEOS SUPPORT (Required):

  The GEOS library provides support for exact topological tests
  such as Touches(), Contains(), Disjoint() and spatial operations
  such as Intersection(), Union() and Buffer().  

    http://trac.osgeo.org/geos/

  OLD NOTE: In order to use the GEOS support, you *may* need to 
  specially compile your version of PostgreSQL to link the C++ runtime library.
  To do this, invoke the PgSQL configuration script this way:
 
  LDFLAGS=-lstdc++ ./configure --your-options-go-here

  The initial LDFLAGS variable is passed through to the Makefile and
  adds the C++ library to the linking stage. 

CONFIGURATION
-------------

To configure PostGIS, run:
	
  ./configure

The results of the configuration can be easily seen within the
postgis_config.h file.

If pg_config can't be found in your $PATH configure will complain
and refuse to proceed. You can specify it using the 
--with-pgconfig=/path/to/pg_config flag.

If PROJ4 has been installed (but cannot be found), configure will
complain and refuse to proceed. You can specify an alternative 
installation directory using the --with-projdir=DIR option.

If GEOS has been installed (but cannot be found), configure will 
complain and refuse to proceed. You can specify an alternative 
geos-config file using the --with-geosconfig=/path/to/geos-config 
option.

See ./configure --help for more options.

BUILD
-----

To build PostGIS library and utilities, as postgres run:

  make
  
INSTALLATION
------------

To install PostGIS library and utilities, as postgres run:

  make install


TESTING
-------

You want to run regress tests after installation.
To do so, as postgres run.  
The below will create a test database with postgis extensions, run tests and then drop the db:

	make check

Final lines of output contain a summary of test results:
run, succeeded, failed. If you have any failure please
file a bug report using the online bug tracker:
http://code.google.com/p/postgis/issues/list.


Installation paths will typically be derived by ``pg_config'':

	- Lib in `pg_config --pkglibdir`
	- Binaries (loader/dumper) in `pg_config --bindir`
	- Important support files in [prefix]/share/contrib
	- Manual pages in [prefix]/man
	- Documentation in in [prefix]/share/doc

Where [prefix] above is extracted by `pg_config --configure`.

You can change them using ./configure switches.
See CONFIGURATION section.

CREATING NEW SPATIAL DATABASES
------------------------------

PostGIS support must be enabled for each database that requires
its usage. This is done by feeding the lwpostgis.sql (the enabler script)
file to the target database. 

The enabler script requires the PL/pgSQL procedural language in order
to operate correctly, you can use the 'createlang' program from the
PostgreSQL installation.
(The PostgreSQL Programmer's Guide has details if you want to do this
manually for some reason.)

So, as postgres run:

  createlang plpgsql <yourdatabase>
  psql -f lwgeom/lwpostgis.sql -d <your_database>

Your database should now be spatially enabled.

UPGRADING EXISTING SPATIAL DATABASES
------------------------------------

Upgrading existing spatial databases can be tricky as it requires
replacement or introduction of new PostGIS object definitions.

Unfortunately not all definitions can be easily replaced in 
a live database, so sometimes your best bet is a dump/reload
process. 

PostGIS provides a SOFT UPGRADE procedure for minor or bugfix
releases, and an HARD UPGRADE procedure for major releases.

--- SOFT UPGRADE ---

Soft upgrade consists of sourcing the lwpostgis_upgrade.sql
script in your spatial database:

  psql -f lwpostgis_upgrade.sql -d your_spatial_database

If a soft upgrade is not possible the script will abort and 
you will be warned about HARD UPGRADE being required,
so do not hesitate to try a soft upgrade first.

--- HARD UPGRADE ---

Hard upgrade is a PostgreSQL dump/restore procedure combined 
with a filter to selectively update PostGIS functions and 
objects to point to a new library version.

Hard upgrades are required when object definitions have changed,
aggregates have changed or been added, and when the underlying
PostgreSQL database itself has undergone a major update.

For this purpose, PostGIS provides a utility script to restore a dump
in "custom" format. The hard upgrade procedure is as follows:

	# Create a "custom-format" dump of the database you want
	# to upgrade (let's call it "olddb")
	$ pg_dump -Fc olddb olddb.dump

	# Restore the dump while upgrading postgis into
	# a new database. 
        # Note: The new database does NOT have to exist.
	# Let's call it "newdb"
	$ sh utils/postgis_restore.pl lwpostgis.sql newdb olddb.dump > restore.log

	# Check that all restored dump objects really had to be 
        # restored from dump and do not conflict with the 
        # ones defined in lwpostgis.sql
	$ grep ^KEEPING restore.log | less

	# If upgrading from PostgreSQL < 8.0 to >= 8.0 you will want to 
	# drop the attrelid, varattnum and stats columns in the geometry_columns
	# table, which are no-more needed. Keeping them won't hurt.
	# !!! DROPPING THEM WHEN REALLY NEEDED WILL DO HARM !!!!
	$ psql newdb -c "ALTER TABLE geometry_columns DROP attrelid"
	$ psql newdb -c "ALTER TABLE geometry_columns DROP varattnum"
	$ psql newdb -c "ALTER TABLE geometry_columns DROP stats"

	# The spatial_ref_sys table is restored from the dump, to 
        # ensure your custom additions are kept, but the distributed 
        # one might contain modification so you should backup your 
        # entries, drop the table and source the new one.
	# If you did make additions we assume you know how to backup them before
	# upgrading the table. Replace it with the new like this:
	$ psql newdb
	newdb=> DELETE FROM spatial_ref_sys;
	DROP
	newdb=> \i spatial_ref_sys.sql


USAGE
-----

Try the following example SQL statements to create non-OpenGIS tables and 
geometries:

  CREATE TABLE geom_test ( gid int4, geom geometry,name varchar(25) );
  INSERT INTO geom_test ( gid, geom, name ) 
    VALUES ( 1, 'POLYGON((0 0 0,0 5 0,5 5 0,5 0 0,0 0 0))', '3D Square');
  INSERT INTO geom_test ( gid, geom, name ) 
    VALUES ( 2, 'LINESTRING(1 1 1,5 5 5,7 7 5)', '3D Line' );
  INSERT INTO geom_test ( gid, geom, name )
    VALUES ( 3, 'MULTIPOINT(3 4,8 9)', '2D Aggregate Point' );
  SELECT * from geom_test WHERE geom && 'BOX3D(2 2 0,3 3 0)'::box3d;

The following SQL creates proper OpenGIS entries in the SPATIAL_REF_SYS
and GEOMETRY_COLUMNS tables, and ensures that all geometries are created
with an SRID.

  INSERT INTO SPATIAL_REF_SYS
    ( SRID, AUTH_NAME, AUTH_SRID, SRTEXT ) VALUES
    ( 1, 'EPSG', 4269,
      'GEOGCS["NAD83",
        DATUM[
          "North_American_Datum_1983",
          SPHEROID[
          "GRS 1980",
          6378137,
          298.257222101
        ]
      ],
      PRIMEM["Greenwich",0],
      UNIT["degree",0.0174532925199433]]'
    );

  CREATE TABLE geotest (
    id INT4,
    name VARCHAR(32)
    );

  SELECT AddGeometryColumn('db','geotest','geopoint',1,'POINT',2);

  INSERT INTO geotest (id, name, geopoint)
    VALUES (1, 'Olympia', GeometryFromText('POINT(-122.90 46.97)',1));
  INSERT INTO geotest (id, name, geopoint)
    VALUES (2, 'Renton', GeometryFromText('POINT(-122.22 47.50)',1));

  SELECT name,AsText(geopoint) FROM geotest;


Spatial Indexes:

PostgreSQL provides support for GiST spatial indexing. The GiST scheme offers 
indexing even on large objects, using a system of "lossy" indexing where 
a large object is proxied by a smaller one in the index.  In the case 
of the PostGIS indexing system, all objects are proxied in the index by 
their bounding boxes.

You can build a GiST index with:

  CREATE INDEX <indexname> 
    ON <tablename> 
    USING GIST ( <geometryfield> );

Always run the "VACUUM ANALYZE <tablename>" on your tables after
creating an index. This gathers statistics which the query planner
uses to optimize index usage.