Re: SSI non-serializable UPDATE performance

Robert Haas <robertmhaas@gmail.com> wrote:
> On Apr 28, 2011, at 9:55 AM, Dan Ports <drkp@csail.mit.edu> wrote:
>> The memory barrier when acquiring the buffer page lwlock acts as
>> the synchronization point we need. When we see that no
>> serializable transactions are running, that could have been
>> reordered, but that read still had to come after the lock was
>> taken. That's all we need: even if another backend starts a
>> serializable transaction after that, we know it can't take any
>> SIREAD locks on the same target while we're holding the buffer
>> page lock.
> 
> Sounds like that might be worth a comment.
There were comments; after reading that post, do you think they need
to be expanded or reworded?:
http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=02e6a115cc6149551527a45545fd1ef8d37e6aa0
-Kevin