On Tue, Feb 28, 2017 at 12:27 AM, Sven R. Kunze <srkunze@mail.de> wrote:
On 27.02.2017 19:22, Jeff Janes wrote:
If by 'permanently', you mean even when you intentionally break things, then no. You will always be able to intentionally break things. There is on-going discussion of an auto-prewarm feature. But that doesn't yet exist; and once it does, a super user will always be able to break it.
Presumably you have a use-case in mind other than intentional sabotage of your caches by root. But, what is it? If you reboot the server frequently, maybe you can just throw 'select pg_prewarm...' into an init script?
I didn't express myself well enough. pg_prewarm doesn't help to speed up those queries at all.
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?