Re: [PERFORM] Can lots of small writes badly hamper reads from other tables?

2012-01-25 Thread Jeff Janes
On Tue, Jan 24, 2012 at 12:16 PM, Dave Crooke dcro...@gmail.com wrote: Hi folks This could be a sheer volume issue, but I though I would ask the wisdom of this forum as to next investigative steps. To answers the question in your subject, yes. If the disk head is positioned to write in one

[PERFORM] Can lots of small writes badly hamper reads from other tables?

2012-01-24 Thread Dave Crooke
Hi folks This could be a sheer volume issue, but I though I would ask the wisdom of this forum as to next investigative steps. We use PostgreSQL 8.4.4 which is bundled with our application as a VMware virtual appliance. The bulk of the app's database activity is recording performance data

Re: [PERFORM] Can lots of small writes badly hamper reads from other tables?

2012-01-24 Thread Andy Colson
On 1/24/2012 2:16 PM, Dave Crooke wrote: Hi folks This could be a sheer volume issue, but I though I would ask the wisdom of this forum as to next investigative steps. We use PostgreSQL 8.4.4 which is bundled with our application as a VMware virtual appliance. The bulk of the app's

Re: [PERFORM] Can lots of small writes badly hamper reads from other tables?

2012-01-24 Thread Tomas Vondra
On 24 Leden 2012, 21:16, Dave Crooke wrote: Hi folks This could be a sheer volume issue, but I though I would ask the wisdom of this forum as to next investigative steps. We use PostgreSQL 8.4.4 which is bundled with our application as a VMware virtual appliance. The bulk of the

Re: [PERFORM] Can lots of small writes badly hamper reads from other tables?

2012-01-24 Thread Dave Crooke
Hi guys Thanks for the quick followups folks please note I am deliberately running a setup without commit guarantees, so a lot of the conventional advice about not doing small writes isn't applicable, but I do want to understand more about how this affects PG internals even if the I/O is

Re: [PERFORM] Can lots of small writes badly hamper reads from other tables?

2012-01-24 Thread Tomas Vondra
On 24.1.2012 22:36, Dave Crooke wrote: Hi guys Thanks for the quick followups folks please note I am deliberately running a setup without commit guarantees, so a lot of the conventional advice about not doing small writes isn't applicable, but I do want to understand more about how this