Re: How clear the cache on postgresql?

I execute the command sync && echo 3 > /proc/sys/vm/drop_caches​ but I
still got buffers hit added to that buffers read now.Why I got the buffers
hit?

2017-11-24 17:55 GMT+01:00 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:

> bricklen <bricklen(at)gmail(dot)com> writes:
> > On Fri, Nov 24, 2017 at 6:54 AM, hmidi slim <hmidi(dot)slim2(at)gmail(dot)com>
> wrote:
> >> I'm trying to analyze some queries using the explain instructions and
> the
> >> option analyze and buffers. I realized that the query refers to the
> cache
> >> memory to return the results. Is there any solution to clear the cache
> in
> >> postgresql inorder to get execution time of the query when it get data
> from
> >> disk and not from cache memory?
>
> > If you are on a (non-production) *nix server you can use:
> > sync && echo 3 > /proc/sys/vm/drop_caches​
>
> You would also need to restart the postmaster, to get rid of whatever
> is in Postgres' shared buffers.
>
> regards, tom lane
>