Re: Heavy write activity on first vacuum of fresh TOAST data

[Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>]

Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)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