[Opensim-users] Are unused assets deleted? (Fred Beckhusen)

[Ethan Gardener]

On Mon, Aug 27, 2018, at 8:06 AM, Haravikk wrote:
> 
> > On 26 Aug 2018, at 15:05, Ethan Gardener <eekee57 at fastmail.fm> wrote:
> > 
> > However, everything I've ever learned about databases says that it's a bad idea to just look at the cost of the disks.  The cost of *accessing* the data (with acceptable performance) goes up exponentially with the size of the dataset.
> 
> This shouldn't be the case; any properly indexed database should have 
> roughly constant, or at worst logarithmic, access times for data.

*sigh* "Logarithmic" is another way of saying "exponential'.  It is not a trivial matter unless the data set is comparatively small.  In asking about these things, I'm particularly thinking of InWorldz, where asset data was growing at a terabyte a month.  Not small.  

> You 
> should only really see big performance drops if the number of assets 
> requests increases beyond what the hardware can cope with (i.e- too many 
> users online simultaneously).
> 
> > There is a solution which I think practically returns the problem to just counting the cost of the disks:  Cache the asset server.  The actual asset server which never deletes anything can then be very slow, with all regularly used assets served from the much faster cache.  
> > 
> > I'm almost certain Second Life implemented such a cache years ago.  I remember when I logged in there after a long absence, things which I'd made or which were old-style took minutes to rez.  I don't ever remember seeing such an effect in InWorldz, so I think it's possible InWorldz didn't have such a cache.
> 
> Most (all?) external asset requests are now served to the viewer via 
> HTTP, so you could use Squid proxy or similar to cache those requests 
> before they touch your asset server, it might even be possible to use a 
> reverse proxy such as Cloudflare to do this for you, though I've never 
> tried it (you might need to use page rules to force it to cache asset 
> URLs).

I'm sure this would help, but wouldn't it miss the case of large vehicles making sim crossings?  A vehicle may be non-physical and not phantom, so the sim needs to know what shape it is and the shape may be complex.  In any case, sim crossings seem to be the first thing to go as a grid grows.