Re: [PERFORM] Kernel cache vs shared_buffers

2007-05-13 Thread Magnus Hagander
Harald Armin Massa wrote: > Heikki, > > >> > PostgreSQL on Windows. My current rule of thumb on Windows: set >> > shared_buffers to minimum * 2 >> > Adjust effective_cache_size to the number given as "system cache" >> > within the task manager. >> >> Why? > > I tried with shared_buffers = 50% of

Re: [PERFORM] Kernel cache vs shared_buffers

2007-05-13 Thread Harald Armin Massa
Heikki, > PostgreSQL on Windows. My current rule of thumb on Windows: set > shared_buffers to minimum * 2 > Adjust effective_cache_size to the number given as "system cache" > within the task manager. Why? I tried with shared_buffers = 50% of available memory, and with 30% of available memor

Re: [PERFORM] Kernel cache vs shared_buffers

2007-05-13 Thread Heikki Linnakangas
Harald Armin Massa wrote: A common rule of thumb people quote here is to set shared_buffers to 1/4 of available RAM, and leave the rest for OS cache. That's probably a good configuration to start with. And just for the record: This rule of thumb does NOT apply to PostgreSQL on Windows. My curre

Re: [PERFORM] Kernel cache vs shared_buffers

2007-05-13 Thread Harald Armin Massa
A common rule of thumb people quote here is to set shared_buffers to 1/4 of available RAM, and leave the rest for OS cache. That's probably a good configuration to start with. And just for the record: This rule of thumb does NOT apply to PostgreSQL on Windows. My current rule of thumb on Window

Re: [PERFORM] Kernel cache vs shared_buffers

2007-05-12 Thread Jim C. Nasby
On Sat, May 12, 2007 at 03:28:45PM +0100, Heikki Linnakangas wrote: > >In the case of it being disk-block based, my > >inclination would be to let the kernel do the buffering. In the case of > >the cache being table-row-based, I would expect it to be much more > >space-efficient and I would be

Re: [PERFORM] Kernel cache vs shared_buffers

2007-05-12 Thread Heikki Linnakangas
Michael van Rooyen wrote: I have no idea regarding the inner working of the pg's shared cache, but what I would like to find out is whether it is table-row-based, or disk-block-based. It's block based. In the case of it being disk-block based, my inclination would be to let the kernel do t

[PERFORM] Kernel cache vs shared_buffers

2007-05-12 Thread Michael van Rooyen
We're in the process of upgrading our db server's memory from 2GB to 8GB to improve access performance. This is a dedicated dual Xeon db server not running any significant non-db processes. Our database size on disk is ~11GB, although we expect it to grow to ~20GB. Much of this data is inact