On 01.03.2017 18:04, Jeff Janes wrote:
On Wed, Mar 1, 2017 at 6:02 AM, Sven R. Kunze <srku...@mail.de
<mailto:srku...@mail.de>> wrote:
On 28.02.2017 17:49, Jeff Janes wrote:
Oh. In my hands, it works very well. I get 70 seconds to do the
{age: 20} query from pure cold caches, versus 1.4 seconds from
cold caches which was followed by pg_prewarm('docs','prefetch').
How much RAM do you have? Maybe you don't have enough to hold
the table in RAM. What kind of IO system? And what OS?
On my test system:
RAM: 4GB
IO: SSD (random_page_cost = 1.0)
OS: Ubuntu 16.04
4GB is not much RAM to be trying to pre-warm this amount of data
into. Towards the end of the pg_prewarm, it is probably evicting data
read in by the earlier part of it.
What is shared_buffers?
942MB.
But I see where you are coming from. How come that these queries need a
Recheck Cond? I gather that this would require reading not only the
index data but also the table itself which could be huge, right?
Sven
