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What are drawbacks of Osmosis Monthly Update?

1

I have made a tile server importing full planet data. I want to keep my database updated to openstreetmap changes using osmosis as explained in this tutorial. This tutorial emphasizes on keeping database updated to minutely or daily changes in openstreetmap data.

My question is that - will there be any problem if I apply osm database update scripts on monthly basis? The tutorial also says that monthly update may take much time as the changeset will be large. Does anyone here have an idea of how much time will it take approximately for applying monthly changesets?[ Given that I am using 1TB SSD for Database, 64GB RAM and 10 virtual cpu ]

asked 17 Aug '18, 14:01

anuranpal's gravatar image

anuranpal
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accept rate: 0%

edited 17 Aug '18, 19:08

aseerel4c26's gravatar image

aseerel4c26 ♦
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One Answer:

5

In my experience, somewhere along the two-week mark there comes the point when a full new data import will be faster than applying diffs. Applying diffs is generally much more "expensive" than importing into a new database, that's why such a point exists. If you settle for a method where you do a full import every month, this also means you can import with the --drop option which will approximately halve your database size. You can then import into a new database, and when done, you delete the old and rename the new. Total disk space needed for this procedure is a bit (maybe 20%?) more than having one full, updatable database, because during the import of the new database a couple of temporary tables are needed. But during normal use your database will be leaner, faster, and not suffer from index bloat.

answered 17 Aug '18, 14:40

Frederik%20Ramm's gravatar image

Frederik Ramm ♦
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accept rate: 23%

@frederik if I use a new database, how will I identify the tile list that needs to be expired? In my case I prerender tiles upto zoom level 13 in disk. So, does it mean that I need to rerender all those tiles as well?

(19 Aug '18, 16:07) anuranpal
2

Typically, what you do in this scenario is you create a file named "planet-import-complete" in your tile directory when you have finished the import. mod_tile will then look at the time stamp of a tile in the cache, and consider it "old" when its time stamp is older than that of the planet import. "old" tiles will then be re-rendered either on the fly or in the background, depending on your setting of the ModTileRequestTimeout configuration option. -- There is no way to explicitly determine which tiles have changed, but after a month, chances are that most tiles have changed anyway!

(19 Aug '18, 16:10) Frederik Ramm ♦

Source code available on GitHub .