1. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Introduction to PostGIS PostGIS Basics for the New User Paul Ramsey & Chris Hodgson Refractions Research

2. OpenSource GIS 2004 Ottawa, Canada www.refractions.net PostgreSQL 1986 : Postgres project at Berkley –Successor to Ingres –Relational Model –Complex Objects –Extensibility 1995 : Postgres95 adds SQL Support 1996 : Open Source Community

3. OpenSource GIS 2004 Ottawa, Canada www.refractions.net PostGIS PostgreSQL 7.1 (Tuple Toaster) Real GIS Support First Release in 2001 OpenGIS “Simple Features for SQL” Current Release 0.8.2

4. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Why PostGIS? Because Databases are Better than Files! Unified Storage, Management, Access –SQL Everywhere Transactional Integrity –Multiple Users, Multiple Edits

5. OpenSource GIS 2004 Ottawa, Canada www.refractions.net PostGIS Users Data Handlers Unified Access Language (SQL) Unified Metadata Location –GlobeXplorer –i-cubed –Refractions

6. OpenSource GIS 2004 Ottawa, Canada www.refractions.net PostGIS Users Real Time Systems Developers Unified Access Language (SQL) Standard Access Protocols –JDBC –ODBC

7. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Team CIMAR : DARPA Grand Challenge

8. OpenSource GIS 2004 Ottawa, Canada www.refractions.net PostGIS Users Spatial Infrastructures LAN WMS / WFS PostGIS Internet JUMP QGIS WFS Client WMS Client

9. OpenSource GIS 2004 Ottawa, Canada www.refractions.net PostgreSQL Version 7.5 Native Windows Support

10. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Windows PostgreSQL \bin Executables \include Include files for compilation \lib DLL shared library files \share Extensions env.bat Command prompt initdb.bat Initialize \data area pgstart.bat Start the database server

11. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Create a Database createdb postgis –Make the database psql postgis –Connect to the database create, insert, select –Try the database

12. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Load PostGIS PostgreSQL Extension –libpostgis.so –postgis.sql Requires PL/PgSQL createlang plpgsql postgis psql -f postgis.sql postgis psql -f spatial_ref_sys.sql postgis

13. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Simple Spatial SQL POINT(5 5) POINT(5 0) POINT(0 5) POINT(0 0)

14. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Load Shape Files select count(*) from bc_roads select count(*) from bc_voting_areas

15. OpenSource GIS 2004 Ottawa, Canada www.refractions.net bc_pubs

16. OpenSource GIS 2004 Ottawa, Canada www.refractions.net bc_roads

17. OpenSource GIS 2004 Ottawa, Canada www.refractions.net bc_hospitals

18. OpenSource GIS 2004 Ottawa, Canada www.refractions.net bc_municipality

19. OpenSource GIS 2004 Ottawa, Canada www.refractions.net bc_voting_areas

20. OpenSource GIS 2004 Ottawa, Canada www.refractions.net bc_voting_areas

21. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Creating Spatial Indexes

22. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Using Spatial Indexes select gid, name from bc_roads where crosses( the_geom, GeomFromText(‘LINESTRING(…)’,42102) ) select gid, name from bc_roads where crosses( the_geom, GeomFromText(‘LINESTRING(…)’,42102) ) and the_geom && GeomFromText(‘LINESTRING(…)’,42102)

23. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Query Plans

24. OpenSource GIS 2004 Ottawa, Canada www.refractions.net #--------------------------------------------------------------------------- # CONNECTIONS AND AUTHENTICATION #--------------------------------------------------------------------------- # - Connection Settings - #listen_addresses = 'localhost'# what IP interface(s) to listen on; # defaults to localhost, '*' = any #port = 5432 max_connections = 100 #superuser_reserved_connections = 2 #rendezvous_name = ''# defaults to the computer name # - Security & Authentication - #authentication_timeout = 60# 1-600, in seconds #ssl = false #password_encryption = true #db_user_namespace = false #--------------------------------------------------------------------------- # RESOURCE USAGE (except WAL) #--------------------------------------------------------------------------- # - Memory - shared_buffers = 1000# min 16, at least max_connections*2, 8KB each #work_mem = 1024# min 64, size in KB #maintenance_work_mem = 16384# min 1024, size in KB #max_stack_depth = 2048# min 100, size in KB #vacuum_cost_page_hit = 1# 0-10000 credits #vacuum_cost_page_miss = 10# 0-10000 credits PostgreSQL Optimization

25. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Data Integrity ValidInvalid

26. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Distance Queries select sum(upbc) as unity_voters from bc_voting_areas where the_geom && setsrid( expand(‘POINT(…)’::geometry,2000) 42102 ) and distance( the_geom, geomfromtext(‘POINT(…)’, 42102) ) < 2000;

27. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Spatial Joins Associate two tables based on a spatial relationship, rather than an attribute relationship.

28. OpenSource GIS 2004 Ottawa, Canada www.refractions.net select m.name, sum(v.ndp) as ndp, sum(v.lib) as liberal, sum(v.gp) as green, sum(v.upbc) as unity, sum(v.vtotal) as total from bc_voting_areas v, bc_municipality m, where v.the_geom && m.the_geom and intersects(v.the_geom, m.the_geom) group by m.name order by m.name;

29. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Overlays Table on table overlays are possible with the Intersection() function. Our example will only overlay one polygon with another table.

30. OpenSource GIS 2004 Ottawa, Canada www.refractions.net create table pg_voting_areas as select intersection(v.the_geom, m.the_geom) as intersection_geom, area(v.the_geom) as va_area, v.*, m.name from bc_voting_areas v, bc_municipality m where v.the_geom && m.the_geom and intersects(v.the_geom, m.the_geom) and m.name = ‘PRINCE GEORGE’;

31. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Coordinate Projection SRID=42102;MULTILINESTRING(( 1004687.04355194 594291.053764096, 1004729.74799931 594258.821943696)) SRID=4326;MULTILINESTRING(( -125.9341 50.3640700000001, -125.9335 50.36378))

32. OpenSource GIS 2004 Ottawa, Canada www.refractions.net Exercises & Questions