[Geocoding] Slow catching up

[Sarah Hoffmann]

Hi Simon,

On Sun, Jan 26, 2014 at 09:43:23AM +0000, Simon Nuttall wrote:
> When I started the installation of a whole planet Nominatim, back in
> early December the initial planet file was already 3 weeks old.
> 
> This was compounded by having an invalid:
> 
> /Nominatim/settings/configuration.txt
> 
> left over from a previous import run, which I did not discover until
> several weeks later.
> 
> So when I fixed that Nominatim was about 6 weeks behind.
> 
> It is going to take about 6 weeks to catch up because it seems to take
> almost an hour to update an hour's changeset, eg these couple of lines
> of output:
> 
> 2014-01-26 09:18:42 Completed index step for 2013-12-05T13:29:02Z in
> 26.8 minutes
> 2014-01-26 09:18:42 Completed all for 2013-12-05T13:29:02Z in 45.85 minutes
> 
> The machine is i/o bound.
> 
> During setup.php I used --threads=2 which made things faster.
> 
> Can more threads be used during update.php - eg I notice there is this option:
> 
> --index-instances
> 
> but would that make a difference?

Using two threads will definitely make a difference although not as much as 
for the import. Going much beyond two threads is not really worth it because the
threads interfere with each other quite a bit. In any case, if your system is
live and serving queries, keep an eye on response times at busy times. Too many
update threads might interfere there, too.

Sarah