Re: Heavy write activity on first vacuum of fresh TOAST data - Mailing list pgsql-performance

From Tom Lane
Subject Re: Heavy write activity on first vacuum of fresh TOAST data
Date
Msg-id 17873.1197571942@sss.pgh.pa.us
Whole thread Raw
In response to Re: Heavy write activity on first vacuum of fresh TOAST data  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
Responses Re: Heavy write activity on first vacuum of fresh TOAST data  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-performance
Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> Simon Riggs wrote:
>> We might be able to have bgwriter set hint bits on dirty blocks,

> I don't think that works, because the bgwriter has no access to the
> catalogs, therefore it cannot examine the page contents.  To bgwriter,
> pages are opaque.

Another issue is that this'd require bgwriter to access the clog SLRU
area.  I seem to remember worrying that that could lead to low-level
deadlocks, though I cannot recall the exact case at the moment.
Even without that, it would increase contention for SLRU, which we
probably don't want.

            regards, tom lane

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