Re: [PERFORMANCE] Buying hardware

On Mon, 26 Jan 2009, David Rees wrote:

> And yes, the more memory you can squeeze into the machine, the better,
> though you'll find that after a certain point, price starts going up
> steeply.  Of course, if you only have a 15GB database, once you reach
> 16GB of memory you've pretty much hit the point of diminishing
> returns.

actually, you need more memory than that. besides the data itself you
would want memory for several other things, among them:

1. your OS
2. your indexes
3. you per-request memory allocations (for sorting, etc)
   this is highly dependant on your workload (type and number of parallel
requests)
4. 'dead' tuples in your table (that will be cleared by a vaccum, but
haven't been yet)

and probably other things as well.

I don't know how large a database will fit in 16G of ram, but I suspect
it's closer to 8G than 15G.

any experts want to throw out a rule-of-thumb here?

David Lang