QGIS & PostGIS,both have something in common. Can you take a quick guess? Yeah,you probably guessed right. It's the GIS in their names. Does this suggest that they are both a GIS software? Well maybe or maybe not. What I do know is that often times,these duo are enough for most of your analysis needs. This section is aimed at introducing you to these powerful duo and at the end would be some helpful resources to help you learn more about them and dive deeper.
TL;DR
C'mon it's not too long,so read it up! Quick expo: You can use the table of contents below to skip to any section of choice :)
- What is PostGIS?
- Why Use PostGIS?
- PostgreSQL/PostGIS Installation
- QGIS Installation
- Connecting QGIS to PostGIS
- Uploading Shapefiles to PostGIS with the Shapefile Loader
- Uploading raster to PostGIS with raster2pgsql & psql
- References
Before diving into PostGIS, I would like us to look into databases briefly. Databases are systems for storing,retrieving and sometimes performing analysis on structured data. It has three major components;
- Functions: These are operations we can perform on the data stored in a database.
- Data Types: These are the kinds and format of data that can be stored in a database.
- Indexes: These are the faster actions and ways to retrieve data from the database.
Let's relate the whole system described above to our local banks. We use our banks to store and retrieve our money(database).There are some acceptable currencies we store in the bank E.g USD,EUR,NGN etc(Data Types),also there are some activities we can perform on our money. E.g transfer,exchange,deposit,invest etc(Functions) and finally there are faster ways we can retrieve our money E.g Point of Sales(POS),Automated Teller Machines(ATMs),Online Banking etc(Indexes).
There are two types of databases--relational(stores data in tabular format i.e rows and columns) and non-relational(stores data in a document format) and the common laguage used for communicating with the database is the SQL(Structured Query Language).
Just like normal databases we have three major components for PostGIS:
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Spatial Data Types
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Spatial Indexes and Bounding Box
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Spatial Functions
PostGIS is an extension to a popular,powerful and free open-source relational database management system called PostgreSQL. It turns the PostgreSQL Database Management System into a spatial database by adding support for the three features described above: spatial types, indexes, and functions. Because it is built on PostgreSQL, PostGIS automatically inherits important “enterprise” features as well as open standards for implementation. The open-source nature of PostGIS gives it the flexibility to use several other open source projects in the backend. Such as the GEOS:The GEOS library provides the necessary algorithms for implementing the SFSQL specification. By linking in GEOS, PostGIS provided complete support for SFSQL by version 0.8.
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Free
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Paul Ramsey,the co-founder of PostGIS calls it a GIS without a GIS :)
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It's easy to install( CREATE EXTENSION POSTGIS;)
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It's can be used for enterprise applications
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PostGIS can connect with several clients e.g QGIS,Geoserver
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and lots more...
This video demonstrates the installation of PostgreSQL 13.1,PGAdmin 4 and PostGIS 3.1 on a windows 10 (64bit) machine using the software installation file downloaded from the official website. As a dark mode fan, I went ahead to customize my PGAdmin 4 to support dark mode(who don't like dark mode anyway?). If you have them installed already you can skip this or watch,you might probably learn a new thing.:)
https://www.youtube.com/watch?v=nmqDkzmxKDU&list=PLz9AoTLQKsZgoiT9UHCDb70KmujjNnhWV&index=2
This video demonstrates the installation of QGIS 3.16 on a windows 10 (64bit) machine using the software installation file downloaded from the official QGIS website.The installation is very straightforward,thanks to QGIS contributors for the well documented website so If you want to install on another operating system,I bet you won't face any issues if you follow the documentation keenly. That's what I did :). If you have QGIS installed already you can skip to the next section.
https://www.youtube.com/watch?v=8qhqihxpUVI&t=20s
PostGIS is not so useful if we stop at the installation and since it's a spatial extension to PostgreSQL I demostrated in this video the uploading of a vector layer(shapefile) to PostGIS using the Shapefile loader that came installed with it and I also did the visualization within PostGIS. Do you know you can visualize data in PostGIS? Well, Check the video to see that.
- PostGIS installation(See above)
https://www.youtube.com/watch?v=KXZGO8S4siA&t=28s&pbjreload=101
This video demonstrates how to install QGIS 3.16 on our windows 10 machine using the software installation file downloaded from the official QGIS website.
- PostGIS installation(See above)
- QGIS installation( See above)
https://www.youtube.com/watch?v=lWDHjQZ7q_g&t=3s
This video demonstrates how to install QGIS 3.16 on our windows 10 machine using the software installation file downloaded from the official QGIS website.
- PostGIS installation(See above)
- QGIS installation( See above)
https://www.youtube.com/watch?v=vAQk9kG3YH4
Actually,It takes me a longer time to make videos than write blogs,so if you feel you don't like these videos,please feel free to tell me what I can improve on in the comments section and feel free to reach me on twitter @jeafreezy I would be very glad to adjust or put a halt to them.
That would be all for now,see you next section!
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Curious on where I got the word GIS without a GIS? Check out this presentaion from Paul Ramsey,PostGIS Co-Founder. at the STL PostGIS Day,2019
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Playlist to dive deeper into Spatial SQl and Postgis by the great Dr. Quiseng wu!
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This interactive learning platform by Crunchy Data is super great to get up and running with learning PostGIS.