911

PostgreSQL Hack

rjhale · Feb 21, 2019 ·

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.

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.

Adding Triggers to Geopackage

rjhale · Aug 30, 2018 ·

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…..

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.

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.

Georgia URISA Luncheon – September 12 2017

rjhale · Sep 6, 2017 ·

Postponed due to Irma

Date: Tuesday September 12, 2017
Time: 11:30 a.m. – 1:30 p.m.
Location:
Cobb County DOT
1890 County Services Parkway
Marietta, GA 30008

“911: Using GIS to Streamline Communication & Reduce Response Time”
Speaker Bio:

Nadine Bennett-Darby is the current Solutions Analyst for Cobb County Department of Transportation Operations Management System. In her current position, Nadine manages, maintains and improves the department’s Operations Management System.

Presentation Summary:

When it comes to 911 calls, every minute counts. Cobb County uses a GIS-based workflow to pass requests from the 911 operator directly into the Department of Transportation’s operations management system. This efficiency streamlines communication during flooding and severe weather events, allows the county to dispatch crews instantly for downed stop signs, and eliminates redundant data entry giving 911 operators back nearly 10,000 minutes a year.

Luncheon Overview: Luncheons are held on the 2nd Tuesday of every month unless otherwise noted. They are intended to provide a social and friendly atmosphere for learning about the successes of our members and to provide opportunities for networking. All are invited to join and students are especially encouraged! You’ll earn 0.1 conference attendance points towards your GISP Certification by attending each luncheon.

Agenda: Meetings are orchestrated according to the following agenda:

11:30 a.m. – 12:00 p.m. – Lunch and Networking
12:00 p.m. – 12:10 p.m. – Announcements
12:10 p.m. – 1:10 p.m. – Presentation
1:10 p.m. – 1:30 p.m. – Discussion

911

Postponed due to Irma

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