[vworld-tech] Database usage

[Brian Hook]

> We have a cache layer over the DB.  Almost nothing is put in the
> cache at load time.  As players log in and access rooms all the
> associated data is read in to the cache.

This is exactly what we're doing.

> The size of the list is tweakable so you could set it to be nearly
> disk-based to have room for the whole db in memory.

What sizes do you typically use, and what metrics do you use to choose 
the size of your cache?  Right now my cache is unbounded, and barring 
a screw up on my part it will scale to size of DB, which I doubt will 
approach multiple GBs (at least, that's my assumption at this point).

> MUD would use the data in a very different way than the website.
> Much more write intensive.  

Yes, which is why I think the cache is a necessity.  Assuming 100 
players executing an average of one "DB operation" per second, and 
then a couple thousand mobs doing likewise, and it adds up.  And if 
those are all writes, and the DB is over a remote link and not running 
locally/embedded, then it's probably heinous.

But it would be nice to be proven wrong (which is one reason for 
starting this thread).

Brian