North River Geographic Systems Inc

Spatial Problem Solving

postgis

FOSS4GNA 2019 – The Short Review

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I tend to spend probably more effort than I should telling people “Go to a FOSS4G Meeting”.

I made my……(think..think… 2013, 2015, 2016, 2017, 2018, 2019) fifth North American Event. Six if you count Boston – but that was International but lets count it – so six.

I think this might be a record for me with consecutive conference attendance. I’m a bit burned out on conferences currently. Usually gis conferences are more of the same – except a FOSS4GNA event isn’t. You never know what’s going to happen. If you make enough of these you become part of the group and to be honest – I could sit in a central area and just talk to people for 3 days. Which I did a lot of….more than I will admit. We talk life, projects, and software.

FOSS4GNA tends to skip around the country – this year it was in San Diego. Which was funny because when I said “Hey I’m going to San Diego people would immediately blurt out ‘OMG You’re going to the conference‘”. Well – no. Not that one – I’m going to the fun one. Jeff Johnson hosted at the Marina Village Conference Center. It was actually a better facility than I gave it credit for at first. It was spread out so you had to be outside. What you ended up doing while walking from one talk to another was stopping and going “Hey I’m in Southern California”. You would at some point stop and sit and not worry about things. Jeff had food trucks swinging by the conference center during breaks – you just wander out and get something. Food was plentiful. Every night there was a social of some sort. You get more done at the socials and over food and drink than you do anything else.

I drifted into more LIDAR talks than normal. I’m a bit blown away at PDAL – I don’t use it for work (yet) but I do play around with it in my spare time. The work going into it and the use cases around it are exciting. I’ve been working with Geoserver more and I went to talks on the new releases that are coming.I bounced into a few QGIS talks. I sat and talked to a lot of people – some that I knew and some that I didn’t. It’s nice hearing what people are doing with FOSS4G software and why people are there. I ran into 3 people from the Southeastern US – and that was nice. I’m not alone in this area screaming into the void.

I did my talk on Henry County’s 911 Server and had some great conversations with people after it was over. It’s nice to see other municipalities drifting into the open source software realm.

I enjoy hearing Paul Ramsey’s Keynotes. He tends to look at the economic side of what we do – that’s an important thing for me. Especially because I make my living doing this and I’m always trying to give back. The synopsis of his talk: Open Source Geo is at it’s “Mid Life” with about 20 years of development. At mid life you sit around and look and there’s not much money for FOSS4G development. There’s plenty in implementation because we are all about selling solutions. If you want to check out the slides – here they are.  What if you took your normal maintenance costs from your commercial software and threw it at an Open Source Project? Maybe hired a developer?

So – I know probably not the best conference summary but it’s hard to summarize the people. That’s really my main attraction to this conference. I can walk into a room of 500 and see people I know and miss people that aren’t there. I can catch up with friends – people are the most important part of this whole thing for me.

What about next year? Next year is the international conference in Calgary….

http://2020.foss4g.org/

….and you should go. I’m going to do my best to get there. Why? People. Come join the community of Free and Open Source Software Community. If you missed out on FOSS4GNA 2019 you missed a good time. If you can’t make 2020 in Calgary keep your eyes open for the next FOSS4G-NA in 2021.

 

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So I’ve been neck deep in Postgresql/Postgis which has been a bit fun but a bit maddening.

One problems I ran into was “What is this column?”. Generally if a client hands me the database I start working with it and do a few things but I don’t worry about their columns in the database. People keep weird things for no reason and I’ve learned to stop asking so many questions on why.

In this case the client had a PDF describing the standard they were working toward. They also had some extra fields they needed for other applications. So I found myself constantly cracking open the PDF or emailing them going “Why is this and what is this?”. If only there was some metadata….

…….but they have this in a PDF and it is good:

So the comment command to the rescue. I’m going to attach the definition to the field: comment on column oirid is ‘leave your comment here’;

Command line magic

Yeah I know that was a lot to add for a comment and I did it all from the magic of the psql command. If I take a look at the table from QGIS using DB Manager now:

View Comments in QGIS.

At this point I know what the column is even if this is a bit overkill. The question is now “Can I get this easy enough to get the client to document their database on the columns I don’t know?”

Actually that’s easy with DBmanager. I can go in and edit an existing table:

Edit your columns in DB Manager

From here I can edit a column and make comments. If I write up some directions the client can jump in and start documenting the more scattered things they have the in database. They can even leave a comment on the table to describe why you have the table.

Comment your columns

I’m constantly overlooking DBManager and the things you can do with it. In this case you can edit an existing table and add comments to help with documenting your database/project. You can import data into PostGIS. You can toss SQL against the database.

PostgreSQL Hack

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Many of you will look and go “OMG – Randy has a new hack for a database”. No – Randy is a hack at databases.

So about 4 or 5 years ago I was dropped into the idea of databases. I was working a job several thousands miles to the south and life was easier with a database as opposed to flat files. Up until that point I had flirted with databases and taken some online courses. I would make small databases but it wasn’t something I had to deal with day to day. I did deal with it indirectly – because at the time my employer was running ArcSDE on top of Oracle – BUT – as a lowly employee I wasn’t allowed to do much with it. That was the job of the admins. I made ESRI File based Geodatabases and was quite happy. Every now and then I’d even make Microsoft Access based ones.

So flash forward to this last year and I’ve been up to my neck in databases. A lot of you will shrug. You do amazing things with PostgreSQL and SQL server and it’s not that big of a deal. Last year I did my third big migration of flat Geo files into PostgreSQL/PostGIS. It was a fairly simple thing to do: QGIS, PostGIS, and I loaded Geoserver (but we still haven’t used it – I’m confident we will).

The client moved from a “ArcView/File based Geodatabse” environment to a multiuser database environment. They are a 911 and it’s a small county. They went from 1 person being able to work to 3 people working and viewing the data. I think currently they have 4 people adding data and updating data now. That’s a win.

My god the dots

What wasn’t a win was my moving of data into the database. File based Geodatabases don’t have a primary key. Maybe there is some way to deal with that these days – I don’t know. So they were using an extension called Attribute Assistant to deal with unique columns and sequences in ArcMap. I loaded the data and didn’t pay enough attention to what was happening.

To make a short story longer – I mucked up the unique column that the data had. I didn’t know it had to be assigned then never change – as explained “it just needs to be unique”. When I loaded it the Primary key and the Unique ID were off. Primary key was 4 and ID was 5. Look there is a primary key of 10 and a ID of 247. The unique ID had nothing to do with the county data – but everything with the state 911 database. So I calc’d the ID off the Primary key and that’s when things went stupid. So what magical GIS thing did I do? I didn’t.

I made a new index column.

update hc911.addresspoints set index = right(oirid, -6)::int;

Which ripped the number off the unique column and assigned it to a new field. I built a new sequence with a new incrementing value. I messed that up. I ended up redefining a new primary key. Fixed. No GIS knowledge applied – just databases.

How do you know you are tired? This is how!

Which – not a huge deal but for me a learning experience. I need to spend one day talking to the client and making out a path way before we migrate. Migrating data took 2 hours. Institutional knowledge probably would have taken 8 hours. The next one won’t have this problem. You’re going to have to talk to me a lot about your data and process. Way more than you want and that’s fine – we just need to talk.

Data is everything. To make everyone happy I set up a few cron jobs to dump data into Geopackage and Shapefiles using OGR. They’ve been quietly chugging along for 6 months now doing their work with no applause or fanfare. More people in the office are slowly going “hey you mean I can use QGIS to connect to the database? I can see the data?”.

I can say this whole move minus the ID hiccup has been a huge win for the organization. I was just lucky enough to be the guy to do it.

So if you’re an organization struggling with your commercial system – why not take a look at this side of the fence. We’re a lot of fun. If you’re wondering “Hey what should I learn these days” – I invite you to dive into PostgreSQL/PostGIS.


20 minutes at the East TN TNGIC Meeting

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I went through a year or so of not talking at conferences. For local ones I’d show up and do something. I taught a workshop at FOSS4GNA 2018. I did a workshop at FOSS4G 2017 in Boston (and it sorta sucked).  I need to get out of that mode and talk more – but I’m happier being quiet these days and working with clients.

Anyway – at FOSS4GNA 2018 I discovered something – the OSGEO Suite had disappeared from Boundless’s Website and was replaced with a github repository. It wasn’t long after Don Meltz put up an excellent explanation of the OSGEO Suite. The OSGEO Suite being gone isn’t a problem. It does increase the amount of talking I have to do spend explaining it’s not a problem. I could even compile the suite – but my clients can’t. They are smart people – but the time to compile the boundless suite won’t be happening.

One of the things I keep running into is the idea of an Open Source Server. The OSGEO Suite was well known and I get people asking “Hey – can you set us up a geo server”. They mean the opengeo suite. I then launch into an explanation of what makes up a “geo server” and they go a bit blank and answer me “Yeah – one of those”.

So for the next bit I’m gonna be doing something like this:

I want to explain how this works to people. We’ve gotten a bit deaf by hearing “ArcServer” at every conference in TN as this one monolithic thing you have to install to make a web map…which really don’t need since AGOL appeared but…you want SDE and it’s not called that and you have two people editing but you need SQl Server but you don’t….

Anyway,  QGIS/PostgreSQL/PostGIS I’ve installed multiple times and as of late I’m experimenting with geoserver and what it can/can’t do. I have no grand delusions of creating ‘Randy’s Open Geo Spatial Super Duper Server’.  I want to get to the point where maybe mapserver is an option in this. So much to learn…so little time.

I suck at github – but I’ve been more active as I try to develop a skill set and get over the angst of pushing and pulling things. I’ve built a vagrant box to install PostGIS/PostgreSQL/Geoserver so I can have something to point at plus it gives me a starting point for an upcoming class I’m in the middle of building. The vagrant box isn’t pretty – I expect to change it over the next bit as it’s mostly pieced together from a lot of other people’s work (Coleman McCormick, Dave Smith, etc). It works though and I have everything but pgadmin 4 running in one spot. Which – I don’t think this is anywhere near “install this for a server” because this is mostly just for talking, training, and testing.

So why vagrant? Why not docker? I can gloss over vagrant faster at theses talks than I can docker.  I have 16 minutes to draw diagrams and about 4 minutes to publish one piece of data: QGIS -> PostGIS -> Geoserver -> Leaflet.

Anyway – if you’re up for the possibility of a train wreck of a presentation come by the East Tennessee Meeting in Kingsport next week as I try to explain how this works and hopefully you get excited enough to install some or all of these components and do something cool with your data.

Adding Triggers to Geopackage

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In between work I get a chance to play around with software. I’ve been digging around postgis more and more these days trying to get a better understanding of what it will do or won’t do. It’s a never ending learning experience for me. Sometimes it pays off – the never ending tutorial left me suggesting we dump a database to a geopackage.

I’m great at using geopackage in sentences like “USE GEOPACKAGE” and “Hey – what do you think about geopackage?”. Since I’m actually officially using it I decided to do some digging. It’s a SQLite container. Since it’s a SQLite container I should be able to do some things with it – like…..

spatialite gui

I can use the spatialite gui and throw SQL against it and change the tables.

While talking to another person the question started with ‘Well – why can’t we just do the data collection in geopackage?’.  Which we did some back and forth and in some cases this would be acceptable vs doing a full postgis install.

So my first question is: Can I make a trigger in a geopackage? The answer is yes. For those of you who don’t know what a trigger does – it responds to some action in a database. In postgresql, I put multiple triggers in a database for a client. Some triggers calculate lengths and some areas and some make a note of who edited a feature.

After some digging I found the syntax and wrote a trigger for SQLite/Geopackage in the form of:

CREATE TRIGGER update_esn AFTER INSERT
ON addresses
BEGIN
update addresspoints set “esn” = (select esn from polygon where st_within(new.geom, geom));
END;

I used the spatialte gui to add the trigger. So if I pass this off to a client they can edit an address and have it automatically pull in the emergency service number. Magic? Eh – close enough for me.

QGIS Screenshot

While it’s not going to work for a multi-user situation (or will it – I’ve not investigated) – it works. So now I’m adding widgets to QGIS to aid in data collection.

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