[OSM-dev] Too many slow queries in db

Tom Hughes tom at compton.nu
Tue Sep 4 09:26:22 BST 2007

In message <20070904091233.p25hyf9pcg80goww at webmail.systemed.net>
        Richard Fairhurst <richard at systemed.net> wrote:

> Tom Hughes wrote:
>> The issue is having a usable database once the data is in, not getting
>> it in there.
> It's only one very very little part of the problem, but we could move  
> GPS traces to a different box.

Not trivial in rails, but I believe it is possible. I don't however
think that it will help much. In the short term it will probably mean
the gps_points table can be cached better which will help but it won't
get round the major problem of the indexes not being able to accurately
locate the desired points or of lock contention with the import daemon.

What we need to do is a combination of looking at an improved index
for gps_points - probably something quadtile based, and maybe moving
it to InnoDB to avoid the lock contention problems.

> They're not joined to anything apart from the users table (are they?),  
> and the latter is sufficiently rarely updated that replication of some  
> sort would be feasible with minimal overhead.

Aside from your code very little joining is done so there should be no
problem having users in a separate database.


Tom Hughes (tom at compton.nu)

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