[OSM-dev] osm2pgsql tile expiry freaks me out
steve at nexusuk.org
Thu Nov 5 16:15:13 GMT 2009
On Wed, 4 Nov 2009, Frederik Ramm wrote:
> corresponding osm2pgsql tile expiry list for zoom level 18 (done with -e
> 18-18) has 5.6 GB and claims to mark dirty a whopping 350 million
Ouch. That sounds very high. However, I don't think I've ever tried
running with "-e 18-18", I use "-e 0-17" on OpenPisteMap.
> As you can see, the average number of edits in a 15-minute window is
> around 50k, but the number of expired tiles varies wildly beyond belief.
I'm not sure you can draw any conclusions from the number of expiries
varying wildly. For example - an edit that changes a single node is only
going to affect a few tiles, whereas an edit that changes a relation made
up of many objects has the potential to affect very large numbers of
> I'm in the process of instrumenting osm2pgsql to find out what changes
> generate these huge tile lists but maybe someone has a hunch.
I'm afraid I can't think of anything off the top of my head, the expiry
stuff was running on OpenPisteMap quite successfully over several months
after I implemented it. Unfortunately, I'm not currently doing updates to
OpenPisteMap (pending some replacement hard disks and Postgres tuning) so
I can't tell you if anything has broken recently.
I'd certainly be interested in anything you find out though.
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Servatis a periculum, servatis a maleficum - Whisper, Evanescence
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