Re: Set hint bits upon eviction from BufMgr

On Mon, Mar 28, 2011 at 10:19 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> On Mon, Mar 28, 2011 at 9:48 AM, Merlin Moncure <mmoncure@gmail.com> wrote:
>>> I was thinking about setting a
>>> flag in the buffer (BM_HEAP) that gets set by the loader which flags
>>> the buffer for later inspection.  Is there a simpler way to do this?
>
>> Hmm.  That's slightly crufty, but it might be OK.  At least, I don't
>> have a better idea.
>
> The major problem with all of this is that the bgwriter has no idea
> which buffers contain heap pages.  And I'm not convinced it's a good
> idea to try to let it know that.  If we get to the point where bgwriter
> is trying to do catalog accesses, we are in for a world of pain.
> (Can you say "modularity violation"?  How about "deadlock"?)

Well, that's why Merlin was suggesting having the backends that read
the buffers in flag the heap pages as BM_HEAP.  Then the background
writer can just examine that bit.

--
Robert Haas
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