Getting Started with PostGIS

© 2015 EnterpriseDB Corporation. All rights reserved. 1
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
4
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
6

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
14
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_l
ine.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
16

Load data from standard to geospatial
17
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
18

Visual Inspection of data
19

•  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>-81.784206000206609,30.2915309995
5613</gml:coordinates></gml:Point>
Geometry Input and Output Functions
20

•  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
21

•  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

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

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