Subject: Overpass API developpement
- From: Igor Brejc <>
- Subject: [overpass] Setting up diffs
- Date: Wed, 26 Jul 2017 19:03:00 +0200
My apologies in advance if these questions have already been answered (I couldn't find anything by googling or reading the docs).
I've been working on setting up my own Overpass API instance (I've assembled instructions for it here: https://wiki.openstreetmap.org/wiki/User:Breki/Overpass_API_Installation). I got everything working except the diffs.
First just some basic information: I've used the cloning mechanism to initially populate the database. Now I have a few of questions:
1. What is the best/preferred way of doing diffs (minutely, hourly, daily, doesn't matter)? I've found at least three ways:
a) fetch_osc.sh + apply_osc_to_db.sh (as described on the wiki page)
b) fetch_osc_and_apply.sh script (found that one in the bin directory, but it's otherwise undocumented)
c) in the "Populating the DB" section, the Overpass wiki page mentions the following, but I don't really understand to exactly which way of populating this refers to:
As a side note, this also works for applying OSC files onto an existing database. Thus you can make daily updates by applying these diffs with a cronjob. This method takes fewer disk loads than minute updates, and the data is still pretty timely
2) When applying diffs on a cloned database, what value of replication_id should I use initially? If replicate_id file holds a value (example) of 10, do I use 9, 10 or 11? When I used 10, the apply_osc_to_db.sh script simply looped without doing anything, but when I use 11, I get a lot of "Way X used in relation Y not found." messages (and also for nodes used in ways), which leads me to believe some diffs were not applied.
3) Both with a) and b) variant I get this kind of error:
By the way, my server has 16 GB of RAM, 512 GB SSD and an 8-core CPU. Running Ubuntu 16.04.2./apply_osc_to_db.sh: line 117: 28219 Segmentation fault (core dumped) ./update_from_dir --osc-dir=$1 --version=$DATA_VERSION $META --flush-size=0+ EXITCODE=139
Any hints would be very appreciated and I will document them on the installation page. Thanks in advance!
- [overpass] Setting up diffs, Igor Brejc, 07/26/2017
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