Re: Page-at-a-time Locking Considerations

On Mon, 2008-02-04 at 13:27 -0500, Tom Lane wrote:
> Simon Riggs <simon@2ndquadrant.com> writes:
> > In heapgetpage() we hold the buffer locked while we look for visible
> > tuples.
> 
> It's a share lock though.  

Which conflicts with write locks.

> Do you have any direct proof that this
> behavior is as nasty as you claim?

No, but I've been thinking about how to get some, for this and other
situations. This one is difficult to track down because it moves from
buffer to buffer reasonably quickly. Starting another thread on that.

We still have a higher than desirable variability in response times and
I'm looking at possible causes.

I'll try patching it, unless you can think of a reason why its a
complete non-starter? I'm not saying we'd want it yet, just that it
seems worth trying.

--  Simon Riggs 2ndQuadrant  http://www.2ndQuadrant.com