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maintain a postgresql database using osm2pgsql


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tarifa    2

hi there good day dear friends, 

 

 

I am trying to maintain a postgresql database using osm2pgsql to maintain my database. 

idea: I want to track the changes made by the daily replication files. do i need to create triggers that fired after delete, update and insert. should i do a daily update process. 

the idea: having a OSM dataset on Postgresql via osm2pgsql. Now I am trying to query all public buildings in UK such as 

 

- hospitals, 
- schools, 
- fire stations and 
- churches. 
- gasoline stations and so on and so forth

 

Well in order to do that, I use something like this query:

 

SELECT *
FROM planet_osm_point pop
WHERE pop.amenity IN ('hospital','fire_station','place_of_worship','school, gasoline stations')

 

well - how do you think about this approach? Is is a good method  do do so!?

 

By looking at the results, it just extracts some of the existing hospitals. i am pretty sure that there are much more hospitals. I can see the red plus logo for hospitals that I also know that they exist there. But it does not show them in the query results.

 

Question: How can I include all of these buildings?

 

assumption: i guess that i am missing those hospitals mapped as areas. We have to run the same query on planet_osm_polygon as well, or we could construct a "union" query: This would come with alot of benefits for the request: That gives us the centrepoints of polygons in addition to the points we have above. 

i guess that we need to use the amenity = 'hospital' from the polygon table and union all with the points. The benefit: it would gives a few more hospitals. The next step needs to be to find out the node, way or relation ID of a hospital that we're missing and query our database for it. 


btw: can i do this with Python - working on the Overpass API

what about the query OSM data with the Overpass API, but how can we use this data now? a idea and a method to download the data is by using the command line tools curl or wget. In order to do this we need to access one of the Overpass API endpoints, where the one we will look go by the format http://overpass-api.de/api/interpreter?data=query. When using curl we can download the OSM XML of our query by running the command

 

curl --globoff -o output.xml http://overpass-api.de/api/interpreter?data=node(1);out;

 

well - the previously crafted query comes after data= and the query needs to be urlencoded. The --globoff is important in order to use square and curly brackets without being interpreted by curl. This query returns the following XML result

 

<?xml version="1.0" encoding="UTF-8"?>
<osm version="0.6" generator="Overpass API 0.7.54.13 ff15392f">
<note>The data included in this document is from www.openstreetmap.org. 
      The data is made available under ODbL.</note>
<meta osm_base="2018-02-24T21:09:02Z"/>  <node id="1" lat="61.4779481" lon="-0.0014863">
    <tag k="historic" v="memorial"/>
    <tag k="memorial" v="stone"/>
    <tag k="name" v="gasoline-station at the corner"/>
  </node></osm>

 

regarding the methods to get the data which method is better and more appropiate?

 

regarding the formats: well we have to say: there are various output formats to choose from in the documentation. In order to download the query result as JSON we need to add [out:json]; to the beginning of our query as in the command: 

 

curl --globoff - o output.json http://overpass-api.de/api/interpreter?data=[out:json];node(1);out;

...giving us the previous XML result in JSON format. You can test the query also in the browser by accessing 

http://overpass-api.de/api/interpreter?data=[out:json];node(1);out;.

which way would you go?

 

look forward to hear from you

Edited by tarifa
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tarifa    2


update: i have found a good and solid manual that describes to get started with open-street-map-to-postgis-the-basics

 

https://www.cybertec-postgresql.com/en/open-street-map-to-postgis-the-basics/


OSM to PostGIS – The Basics
Ever wondered how to import OSM (OpenStreetMap) data into PostGIS [1] for the purpose of visualization and further analytics? Here are the basic steps to do so. There are a bunch of tools on the market— osm2pgsql; imposm; ogr2org; just to mention some of those. In this article I will focus on osm2pgsql [2].

Let’s start with the software prerequisites. PostGIS comes as a PostgreSQL database extension, which must be installed in addition to the core database. Up till now, the latest PostGIS version is 3, which was released some days ago. For the current tasks I utilized PostGIS 2.5 on top of PostgreSQL 11.
This brings me to the basic requirements for the import – PostgreSQL >= 9.4 and PostGIS 2.2 are required, even though I recommend installing PostGIS >=2.5 on your database;  it’s supported from 9.4 upwards. Please consult PostGIS’ overall compatibility and support matrix [3] to find a matching pair of components.

Osm2pgsql Setup
Let’s start by setting up osm2pgsql on the OS of your choice – I stick to Ubuntu 18.04.04 Bionic Beaver and compiled osm2gsql from source to get the latest updates.

Install required libraries

sudo apt-get install make cmake g++ libboost-dev libboost-system-dev \
libboost-filesystem-dev libexpat1-dev zlib1g-dev \
libbz2-dev libpq-dev libproj-dev lua5.2 liblua5.2-dev
Grab the repo

git clone https://github.com/openstreetmap/osm2pgsql.git
Compile

mkdir build && cd build
cmake ..
make
sudo make install
If everything went fine, I suggest checking the resulting binary and its release by executing

./osm2pgsql-version. 
osm2pgsql version 1.0.0 (64 bit id space)
[/CODE]

 

[B]Data acquisition[/B]In the world of OSM, data acquisition is a topic of its own, and worth writing a separate post discussing different acquisition strategies depending on business needs, spatial extent and update frequency. I won’t get into details here, instead, I’ll just grab my osm data for my preferred area directly from Geofabrik, a company offering data extracts and related daily updates for various regions of the world. This can be very handy when you are just interested in a subregion and therefore don’t want to deal with splitting the whole planet osm depending on your area of interest – even though osm2pgsql offers the possibility to hand over a bounding box as a spatial mask. As a side note – osm data’s features are delivered as lon/lat by default.

So let’s get your hands dirty and fetch a pbf of your preferred area from Geofabrik’s download servers [4] [5]. For a quick start, I recommend downloading a dataset covering a small area:

[CODE]wget https://download.geofabrik.de/europe/iceland-latest.osm.pbf[/CODE]

[/QUOTE]

 

here is another guide - the Part 1: [B]Loading OpenStreetMap data into PostGIS: An Almost Idiot's Guide[/B]
[url]https://www.bostongis.com/PrinterFriendly.aspx?content_name=loading_osm_postgis[/url]

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