Re: GUC with units, details

On Jul 27, 2006, at 6:10 , Martijn van Oosterhout wrote:

> The thing is, most memory sizes in postgres need to be some  
> multiple of
> a page size. You can't have a shared buffers of exactly 100000 bytes,
> while 102400 bytes is possible.

I've seen this mentioned a couple of times. I'm not nearly as  
familiar with these settings as I should be, but it seems to me that  
if the memory size *does* need to be a integral multiple of page  
size, e.g., n * page_size = memory_size,  why isn't that memory  
configured as the integer n rather than memory_size? Wouldn't this  
get around the issue altogether? Granted, this is a larger change  
than allowing units for the values, which I think is a good thing.  
But it is perhaps shows more clearly the relationship between the  
different values in postgresql.conf and prevents setting memory sizes  
that *aren't* multiples of page size.


Michael Glaesemann
grzm seespotcode net