Re: CLOG contention - Mailing list pgsql-hackers

From Tom Lane
Subject Re: CLOG contention
Date
Msg-id 14387.1325793421@sss.pgh.pa.us
Whole thread Raw
In response to Re: CLOG contention  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: CLOG contention  (Simon Riggs <simon@2ndQuadrant.com>)
Re: CLOG contention  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> I would like to do that, but I think we need to at least figure out a
> way to provide an escape hatch for people without much shared memory.
> We could do that, perhaps, by using a formula like this:

> 1 CLOG buffer per 128MB of shared_buffers, with a minimum of 8 and a
> maximum of 32

I would be in favor of that, or perhaps some other formula (eg, maybe
the minimum should be less than 8 for when you've got very little shmem).

I think that the reason it's historically been a constant is that the
original coding took advantage of having a compile-time-constant number
of buffers --- but since we went over to the common SLRU infrastructure
for several different logs, there's no longer any benefit whatever to
using a simple constant.
        regards, tom lane


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