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PostGIS - Geographic Information Systems Extensions to PostgreSQL ~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ VERSION: 1.0.0 (2005/01/13) MORE INFORMATION: http://postgis.refractions.net INTRODUCTION: 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. ./lwgeom Library source code. ./jdbc Extensions to the PostgreSQL JDBC drivers to support the GIS objects. ./doc Documentation on the code, objects and functions provided. ./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.. ./examples Small programs which demonstrate ways of accessing GIS data. INSTALLATION: PostGIS is compatible with PostgreSQL 7.2 and above. To install the module, move this directory to the "contrib" directory of your PostgreSQL source installation. Alternately, point PGSQL_SRC at your PostgreSQL source tree either in an environment variable or editing Makefile.config. You *must* have a PostgreSQL source tree, and you *must* have succesfully built and installed it for this to work. SEE THE NOTE ON GEOS SUPPORT BELOW FOR SPECIAL COMPILATION INSTRUCTIONS * PROJ4 SUPPORT (Recommended): The Proj4 reprojection library is required if you want to use the transform() function to reproject features within the database. http://www.remotesensing.org/proj Install Proj4 in the default location. Edit the postgis Makefile.config and change the USE_PROJ variable to 1 and ensure that the PROJ_DIR variable points to your Proj4 installation location (/usr/local is the default). * SPATIAL PREDICATE / GEOS SUPPORT (Recommended): The GEOS library provides support for exact topological tests such as Touches(), Contains(), Disjoint() and spatial operations such as Intersection(), Union() and Buffer(). http://geos.refractions.net 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. Once you have compiled PgSQL with C++ support, you can enable GEOS support in PostGIS by setting the USE_GEOS variable in the PostGIS Makefile.config to 1, and ensure that the GEOS_DIR variable points to your GEOS installation location (/usr/local is the default). To compile PostGIS, as root run: make make install PostGIS now requires the PL/pgSQL procedural language in order to operate correctly. To install PL/pgSQL use the 'createlang' program from the PostgreSQL installation. (The PostgreSQL Programmer's Guide has details if you want to this manually for some reason.) As postgres run: createlang plpgsql yourdatabase psql -f lwpostgis.sql -d yourdatabase Installation should now be complete. UPGRADING: Upgrading PostGIS can be tricky, because the underlying C libraries which support the object types and geometries may have changed between versions. For this purpose PostGIS provides an utility script to restore a dump produced with the pg_dump -Fc command. It is experimental so redirecting its output to a file will help in case of problems. The procedure is as follow: # 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 contextually upgrading postgis into # a new database. The new database doesn't 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 < 7.5 to >= 7.5 you might 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 HURT !!!! $ 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" # spatial_ref_sys table is restore 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 of it with the new one is done like this: $ psql newdb newdb=> drop table spatial_ref_sys; DROP newdb=> \i spatial_ref_sys.sql Following is the "old" procedure description. IT SHOULD BE AVOIDED if possible, as it will leave in the database many spurious functions. It is kept in this document as a "backup" in case postgis_restore.pl won't work for you: pg_dump -t "*" -f dumpfile.sql yourdatabase dropdb yourdatabase createdb yourdatabase createlang plpgsql yourdatabase psql -f lwpostgis.sql -d yourdatabase psql -f dumpfile.sql -d yourdatabase vacuumdb -z yourdatabase 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.