Re: [GENERAL] Enough RAM for entire Database.. cost aside, is this

2004-07-09 Thread Harald Fuchs
In article <[EMAIL PROTECTED]>, Edmund Dengler <[EMAIL PROTECTED]> writes: > But on the other hand, general algorithms which are designed to work under > a wide variety of circumstances may fail in specific cases. I am thinking > of VACUUM which would kill most caching algorithms simply because we

Re: [GENERAL] Enough RAM for entire Database.. cost aside, is this

2004-07-08 Thread Edmund Dengler
Greetings! On Fri, 2 Jul 2004, Mike Rylander wrote: > I find that experience does not bear this out. There is a saying a coworker > of mine has about apps that try to solve problems, in this case caching, > that are well understood and generally handled well at other levels of the > "software st

Re: [GENERAL] Enough RAM for entire Database.. cost aside, is this

2004-07-07 Thread Andy B
> It's not that making the cache bigger is inefficient, it's that the cache is > not used the way you are thinking. Ok, I think I've got it now. The missing piece of the puzzle was the existence of the Linux buffer cache. So that's what the effective_buffer_cache value is for(!) I read Shridhar

Re: [GENERAL] Enough RAM for entire Database.. cost aside, is this

2004-07-07 Thread Andy B
>If all the data fits into memory, then this cache thrashing won't occur, yes? No - it *can* occur in a 2 tier cache strategy. The critical question here is: *If* the data postgresql needs is in the linux buffer cache, what (if anything) does the OS have to do to make it available to the postmas

Re: [GENERAL] Enough RAM for entire Database.. cost aside, is this

2004-07-07 Thread Andy B
Hello again Mike, Thanks for the replies! Here's my next salvo! > Perhaps I'm a bit naive about complex data structure caching strategies, but > it seems to me that the overhead of tracking tuples (which is what you > would want if you are going to manage your own cache, as opposed to simply > ca

Re: [GENERAL] Enough RAM for entire Database.. cost aside, is this

2004-07-07 Thread Andy B
Hello Shridhar, Thanks for the reply. > There is no reason why you should not do it. How remains to be a point of > disagreement though. You don't allocate 16GB of shared buffers to postgresql. > That won't give you performance you need. I think in the other thread, Tom was alluding to this too.

Re: [GENERAL] Enough RAM for entire Database.. cost aside, is this

2004-07-07 Thread Andy B
> There's a good bit of depth in the archives of this list. I would start > searching back for discussions of effective_cache_size, as that is involved > in *costing* the caching job that the OS is doing. Thanks - that's just what I need to sink my teeth into. I'll have a trawl and get back later

Re: [GENERAL] Enough RAM for entire Database.. cost aside, is this going to be fastest?

2004-07-03 Thread Soeren Gerlach
> Briefly, my problem: > -- > I expect the database I'm working on to reach something in the order of > 12-16 Gigabytes, and I am interested in understanding as much as I can > about how I can make this go as fast as possible on a linux system. I > haven't run such a large database