On Wed, Mar 1, 2017 at 6:02 AM, Sven R. Kunze <[email protected]> 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?
Cheers,
Jeff
