[Tile-serving] Unable to serve tiles using latest instructions to build your own OSM tile server

[Pawan Singh]

Thanks for the response.

Let me try to see if I can debug PostGreSql query performance.

How does one go about pre-rendering z0-z12 tiles and how much disk space would they take for "planet.pbf" file?

Thanks
Pawan

________________________________________
From: Frederik Ramm <frederik at remote.org>
Sent: Wednesday, October 21, 2015 11:08 PM
To: tile-serving at openstreetmap.org
Subject: Re: [Tile-serving] Unable to serve tiles using latest instructions to build your own OSM tile server

Hi,

On 10/22/2015 06:41 AM, Pawan Singh wrote:
> I did not get any response for this.

How many days did you give the volunteers who read and write here in
their spare time before deciding that the level of free support offered
by OSM wasn't for you?

If you do not want to rely on free advice given by volunteers, you can
indeed buy ready-made tiles from various vendors like you say, or you
could also pay someone to help you debug your problem - see
http://wiki.openstreetmap.org/wiki/Commercial_OSM_Software_and_Services
for a list of people who might be able to help professionally.

> I kept on debugging. It seems like PostGreSQL is having issues getting
> the information from the db. I checked all indices. They are all built
> and ready.

Even with good and working indexes it would not be surprising if certain
tiles on certain zoom levels - most notoriously in the z6 to z9 range -
would take more than half an hour to render. I haven't ever heard of
benchmarks with EBS, you might be the first to try that - but generally
the random I/O performance on the Amazon platform seems to be a bit
lacking. For a tile server, nothing beats a plain old non-cloud
non-virtual server with simple SSDs.

In any case you would usually pre-render z0-z12 or so. But any tile
server should be able to render a z16 tile on the fly. If your server
fails to even do that, then switch on statement logging in your
PostgreSQL (log_statement=all), look at a couple of queries that are
made during rendering, and run them manually with "EXPLAIN ANALYZE" to
see if the indexes are actually used. -- I've seen freak cases where for
some reason a lack of "ANALYZE" made the query planner think it could do
a sequential scan of the polygon table or so.

16 GB of RAM should work but I'd recommend 32 GB - mind you, if the disk
performance sucks then the extra GB won't help much.

Bye
Frederik

--
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"

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