Re: Serializable Isolation without blocking

On Thu, 2009-05-07 at 15:10 -0500, Kevin Grittner wrote:
> The assertion that
> there is some need for each session to wade through something for
> every other session seems baseless to me.  I'm wondering what I might
> be missing.

That's Greg's point. Do we need full locking of everything we might
touch, or tracking of what we have touched? That question is still
unanswered.

If you need the "might touch" then you either need to implement locking
that will effect everybody (which ain't ever gonna fly round here), or
you implement a scheme that is harder work but avoids locking. That is
clearly O(N^2) for non-locking design.

If you track "have touched" only then we can do that with a hash table
in shared memory. That would be O(k), if it is possible.

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Training, Services and Support