Getting Started with PostGIS

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Getting started with PostGIS Adam Wright – Database Consultant


•  Introduction to EDB

•  A little bit about Postgres •  About PostGIS

•  Geospatial basics •  Now, let us get started •  Maintenance

Agenda


POSTGRES innovation

ENTERPRISE reliability

24/7 support

Services & training

Enterprise-class features, tools &

compatibility

Indemnification

Product road-map

Control

Thousands of developers

Fast development

cycles

Low cost

No vendor lock-in

Advanced features

Enabling commercial adoption of Postgres


Postgres: A Proven Track Record •  Most mature open source DBMS technology

•  Enterprise-class features (built like Oracle, DB2, SQL Server)

•  Strong, independent community driving rapid innovation

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Fully ACID Compliant MVCC

Point in Time Recovery (PITR) ‏Data and Index Partitioning

Bitmap Indexes ANSI Constraints

Triggers & Stored Functions Views & Data Types Nested Transactions

Online Backup Online Reorganization

Foreign Keys Streaming Replication

Multi-Core Support JSON Support

Hstore Table Partition

Materialized Views Grouping Sets and CUBE (9.5)

UPSERT (9.5) Row Level Security (9.5)


Scalable


•  Refractions Research released first version in 2001 under the GNU license

•  Follows the Simple Features for SQL specification from the Open Geospatial Consortium (OGC)

•  Spatial operators and spatial functions •  Spatial data types

•  Spatial indexing •  Spatial reprojection •  Import / Export Esri shapefiles

•  Commands for importing raster data •  SQL to render and import data from multiple

formats

About PostGIS

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PostGIS Data Types Geometry

Geography

Raster Topology


PostGIS Data subtypes

Point

Linestring

Polygon

Multipoint

Multilinestring

Multipolygon


Spatial Definitions Examples (1 of 5)

Boundary





Contains



Equals




•  Repository

•  Binary

Step 1: Install PostGIS - two methods

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RedHat ‘yum install postgis2_94’

Debian ‘apt-get install postgres-9.4-postgis’


•  For a New Database CREATE DATABASE geodb WITH template = template_postgis;

•  For an Existing Database CREATE EXTENSION postgis; CREATE EXTENSION postgis_toplogy;

•  Verify SELECT postgis_version();

Step 2: Enable PostGIS


•  Load shapefiles shp2pgsql –c –s 4629 –I /tmp/boston_massachusetts_osm_line.shp boston_osm_line | pgsql –d geodb

•  Inserting a point in SQL INSERT into cities(name,state,geom)

Values(‘Boston’,’MA’, ST_GeomFromText(‘POINT(-71.0589 42.3601)’,4326));

Step 3: Load Data

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Load data from standard to geospatial

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INSERT into events_geo(eventname,geom,date) SELECT eventname, st_setsrid(st_makepoint(lon,lat),4326) as geom,date FROM events;

Events Table eventname – character varying

lat - double precision lon - double precision

Date - timestamp with time zone

Events_geo Table eventname - character

varying geom – geometry (Point,4326)

Date – timestamp with time zone

INSERT


Visual Inspection of data

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Visual Inspection of data

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•  Output geometry data types to other data types SELECT st_astext(geom), st_asgeojson(geom), stasgml(geom) FROM atm_locations LIMIT 1; -[ RECORD 1 ]+----------------------------------st_astext | POINT(-81.7842060002066 30.2915309995561)

st_asgeojson | {"type":"Point","coordinates":[-81.7842060002066,30.2915309995561]} st_asgml | <gml:Point srsName="EPSG:4629"><gml:coordinates>-81.784206000206609,30.29153099955613</gml:coordinates></gml:Point>

Geometry Input and Output Functions

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•  Create geometry type from text Insert into cities (name,state,geom)

Values (‘Bedford’,’MA’, ST_GeomFromText(‘POINT(-71.248063 42.510547)’,4326));

Geometry Input and Output Functions

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•  Write a function to tell whether a given lat/lon pair is within a Point-Radius ring IF ST_Dwithin(check_pt, point_pt, outerRadius) AND NOT ST_Dwithin(chevk_pt, point_pt, innerRadius)

THEN return 1; ELSE

Return 0;

END IF;

•  Create a route from a collection of waypoints captured in sequence CREATE TABLE PATHS as SELECT routeid, seq, geom FROM waypoints ORDER BY seq) a GROUP BY routeid;

Power of GIS & SQL


•  Simple distance query between two points

SELECT ST_Distance (ST_GeomFromText ('POINT(34 9)’,4629), ST_GeomFromText ('POINT(70 12)’,4629));

Power of GIS & SQL

34, 9 70, 12


•  Write a function to tell whether a given lat/lon pair is within a Point-Radius ring IF ST_Dwithin(check_pt, point_pt, outerRadius) AND NOT ST_Dwithin(chevk_pt, point_pt, innerRadius)

THEN return 1;

ELSE Return 0;

END IF;

•  Create a route from a collection of waypoints captured in sequence CREATE TABLE PATHS as SELECT routeid, st_make(gem) as geom FROM (SELECT routeid, seq, geom FROM waypoints ORDER BY seq)a GROUP BY routeid;

Power of GIS & SQL


•  Answer powerful questions with a simple query −  Input function

Insert into cities (name,state,geom)

Values (‘Bedford’,’MA’,

ST_GeomFromText(‘POINT(-71.248063 42.510547)’,4326));

Power of GIS & SQL


Power of GIS & SQL


Power of GIS & SQL


Maintenance of a PostGIS database

•  After bulk inserts and updates – VACUUM ANALYZE •  Loading large dataset: Build indexes after •  Use EXPLAIN

•  Add Indexes on PostGIS columns •  Backup/Recovery and SR considerations


•  Power of Postgres −  Binary replication, Table Partitions, Text search function and operators, PL/SQL, PL/Python,

PLV8, PL/R, Indexes −  Grouping sets, cube and rollup (now in EDB Postgres Plus, coming in Postgres 9.5) −  Foreign table inheritance (new in 9.5)

•  ogr2ogr

•  Web Maps −  Open Layers −  Map Server −  GeoServer

Notes:


Getting Started with PostGIS

Software