| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Clock with Adaptive Replacement |
| Date: | 2016-02-15 22:33:57 |
| Message-ID: | 12600.1455575637@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> writes:
> On 2/12/16 9:55 AM, Robert Haas wrote:
>> I think it's important to spend time and energy figuring out exactly
>> what the problems with our current algorithm are. We know in general
>> terms that usage counts tend to converge to either 5 or 0 and
>> therefore sometimes evict buffers both at great cost and almost
> Has anyone done testing on the best cap to usage count? IIRC 5 was
> pulled out of thin air.
My recollection is that there was some testing behind it ... but that
was back around 2005 so it seems safe to assume that that testing
is no longer terribly relevant. In particular, I'm sure it was tested
with shared_buffer counts far smaller than what we now consider sane.
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Noah Misch | 2016-02-15 22:52:31 | postgres_fdw vs. force_parallel_mode on ppc |
| Previous Message | Tom Lane | 2016-02-15 22:27:47 | Re: Re: Reusing abbreviated keys during second pass of ordered [set] aggregates |