Using MapServer with PostgreSQL / PostGIS

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Using MapServer

with

PostgreSQL / PostGIS

D.Magni, Using MapServer with PostgreSQL / PostGIS

GIS (A) - 2006/2007

(Creative Commons by-nc-sa, 3.0)

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1. PostgreSQL

ORDBMS : Object oriented Relational DataBase Management System

Link : http://www.postgresql.org/

Release for exercises : 8.2 for Windows

with PostGIS

with pgAdmin III

OpenSource License : BSD

D.Magni, Using MapServer with PostgreSQL / PostGIS(Creative Commons by-nc-sa, 3.0)

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2. PostGIS

“PostGIS adds support for geographic objects to the PostgreSQL object-relational database. In effect, PostGIS "spatially enables" the PostgreSQL server, allowing it to be used as a backend spatial database for geographic information systems (GIS)” (citation from PostGIS website)

Link : http://postgis.refractions.net/

Release for exercises : 8.2 for Windows

OpenSource License : GPL (General Public License)


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2. PostGIS

Allows to geo-refer tables of PostgreSQL (tables become spatial tables)

This is possible by adding a Geometry Column to tables

The Geometry Column (type=geometry) contains data with the syntax:

SRID=<crs_id>;<GEOMETRY_TYPE>(<COORDINATES>,<COORDINATES>)

Example:

SRID=3003;LINESTRING(1503032.67 5071234.09,1503052.55 5073234.21)

For Gauss-Boaga (West) SRID=3003; if the CRS is not specified, set SRID=-1


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2. PostGIS

<GEOMETRY_TYPE> can be:

POINT(0 0)

LINESTRING(0 0,1 1,1 2)

POLYGON((0 0,4 0,4 4,0 4,0 0),(1 1, 2 1, 2 2, 1 2,1 1))

MULTIPOINT(0 0,1 2)

MULTILINESTRING((0 0,1 1,1 2),(2 3,3 2,5 4))

MULTIPOLYGON(((0 0,4 0,4 4,0 4,0 0),(1 1,2 1,2 2,1 2,1 1)),

((-1 -1,-1 -2,-2 -2,-2 -1,-1 -1)))

GEOMETRYCOLLECTION(POINT(2 3),LINESTRING((2 3,3 4)))


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2. PostGIS

A DB spatially enabled by PostGIS has two special tables:

geometry_columns: contains a row for each spatial table of that DB

spatial_ref_sys: is a list of CRSs, like the EPSG file seen for PROJ library


Name of the spatial table

Name of geometry columnGeometry dimensions

CRS (SRID) Geometry type


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3. pgAdmin III

Frontend application for working with PostgreSQL without command line

Link : http://www.pgadmin.org/

Release for exercises : 1.6.2 for WindowsLicense : http://www.pgadmin.org/licence.php

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4. Exercises

1. Open pgAdmin III on your local PC (Start Programs PostgreSQL pgAdmin III)2. Connect the PostgreSQL remote server

File Aggiungi serverFile Add server

4.1 - Connect a remote PostgreSQL server

A - Service name: GIS course

AB

B - Host name: 192.168.157.30C – Manager DB: gisD - User name: ugisNRE - Password: ugisNR

CDE

3. Click OK

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NR is the same number of your PSF;Example: psf34 ugis34


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4. Browse the server tree

Tablesgeometry_columns

spatial_ref_sys

Database


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1. Tabelle Nuova tabella Tables New table

4.2 – Create a table

Name = tableNR

Holder = your user

With OID (select checkbox)

Then, OK

Properties

NR is yourPSF number

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Column name = id

Column type = integer

Is not null (select checkbox)

Then, OK

Columns


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Columns

Insert a new column:Name = nameType = character varyingLength = 25

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Constraints


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1) Choose a primary key

2) Click Aggiungi (Add)

3) Choose columns tab

4) Select id column as primary key

5) Click Aggiungi and OK

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Confirm table creation with OKCorrespondent SQL statements


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1. Open Free SQL Box

2. Write the SQL statement:

SELECT AddGeometryColumn(‘<dbName>’,’<tableName>’,

’<geometryColumnName>’,<SRID>,’<geometryType>’,

<geometryDimension>);

3. For the table just created write:

SELECT AddGeometryColumn(‘gis’,’tableNR’,’coord’,3003,’POINT’,2);

4.3 – Add a Geometry Column


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4.3 – Add a Geometry Column


4. Confirm with Run button

5. Check result


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2. Write the SQL statement:

CREATE INDEX <indexName>

ON <tableName>

USING GIST ( <geometryColumnName> );

4.4 – Add a GiST index

3. Confirm the SQL statement

Here:

CREATE INDEX mygistNR ON tableNR USING GIST ( coord );


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Primary key

Table columns

GiST index

Geometry column indexes


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4.5 – Populate a table

1. Select the table2. Right click on the table name

and select Visualizza dati (View data)

3. Choose if display all rows (Mostra tutte le righe), first 100 rows (Visualizza le prime 100 righe) or filtered rows (Visualizza righe filtrate...)

or

1. Select the table2. Click on A to display all rows

or B to display filtered rows

A B


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4.5 – Populate a table

4. Fill in the rows (id,name,coord) as shown in the example

5. Don’t fill in oid: PostgreSQL does it automatically6. Press Enter to confirm

Open Free SQL Box and writeINSERT INTO <tableName>(<column1>,<column2>,...)

VALUES (<value1>,<value2>,...);

If all columns are populated, <column1>,<column2>,... specification can be omitted

Here write:INSERT INTO table1 VALUES (2,’Monte Tre Croci’,

’SRID=3003;POINT(1507871 5070661)’);

It’s possible to populated tables by SQL directly (standard mode)


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Web Server

Template file(HTML)

CGI

Map file

BROWSER

2

1

3

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PostgreSQLData

Spatially DBMS enabler

3.a4.b

4.a

3.b

4.6 – Display a PostgreSQL spatial table with MapServer

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Architecture


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1. Open your map file2. Write a new layer to load PostgreSQL/PostGIS data:


LAYER

NAME "layername"

TYPE point

STATUS default

CONNECTIONTYPE postgis

CONNECTION "dbname=<db> host=<host> port=5432 user=<user> password=<pwd>"

DATA "<geometryColumn> from <tableName>"

CLASS

NAME "voice of legend"

STYLE

COLOR 255 0 255

SYMBOL "45rotated_cross"

END

END

END

Geometry column from table

Connection by PostGISConnection parameters

If PostgreSQL and MapServer share the same host,it’s possible to write host=127.0.0.1 or host=localhost


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3. Write a layer for tableNR data

4. Check that the layer is correctly drawn in the map

5. Insert other 5 rows in your tableNR and see the result on the map



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It’s possible to convert a PostgreSQL/PostGIS table to a shapefile

• Open an MS-DOS command prompt• Enter the folder of your local PostgreSQL installation (refer to it as

$PostgreSQL), by cd command• Enter 8.2\bin\ folder• Run the pgsql2shp command, with the following syntax:

pgsql2shp -h [hostName] -u [PostgreSQLUserName] -P

[password] -f [path\NewShapefileName] [dbName]

[tableName]

4.7 – PostgreSQL table to shapefile conversion

Number of table rows converted to shapefile features

5. Check that the output message is :


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6. Convert your tableNR to a new shapefile:

pgsql2shp -h [hostName] -u [PostgreSQLUserName] -P

[password] -f C:\Temp\tableNR gis tableNR

4.7 – PostgreSQL table to shapefile conversion

7. Open target folder and check that the new shapefile has been created correctly (.shp, .shx, and .dbf files)

8. Open it in a desktop GIS (e.g. ArcGIS) and verify its structure


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It’s also possible to convert a shapefile to a PostgreSQL/PostGIS table.

• Open an MS-DOS command prompt• Enter the folder of your local PostgreSQL installation (refer to it as

$PostgreSQL), by cd command• Enter 8.2\bin\ folder• Run the shp2pgsql command, with the following syntax:

shp2pgsql -c -s [SRID] -g [geometryColumnName] -I

[path\ShapefileName.shp] [newTableName] >

[path\outputFilename.sql]

-c means that the table is created and populated (other options are: -a: append shapefile into a current table; -d: drop the table and recreate it with shapefile data; ù-p: only create the table, without populating it.-I creates a GiST index for the new table

4.8 – Shapefile to PostgreSQL table conversion

5. Check that the output message is :

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7. Load your .sql file (A)

8. Run the SQL statement (B)

9. Check that the table has been created properly

4.8 – Shapefile to PostgreSQL table conversion

A B


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PostgreSQL documentation: http://www.postgresql.org/docs/

PostGIS documentation: http://postgis.refractions.net/documentation/

gdAdmin III documentation: http://www.pgadmin.org/docs/

Loading PostgreSQL/PostGIS tables in MapServer: http://mapserver.gis.umn.edu/docs/reference/mapfile/layerhttp://postgis.refractions.net/docs/ch04.html#id2879503

Atzeni P., Ceri S., Peraboschi S., Torlone R. (1999). “Basi di dati” - McGraw-Hill

Documentation and References


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Last update: 24/10/2007


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Using MapServer with PostgreSQL / PostGIS