On 22 March 2017 at 01:49, Robert Haas <robertmhaas@gmail.com> wrote:
> /me smacks forehead. Actually, it should be CLogTruncationLock, with
> a capital L, for consistency with CLogControlLock.
Will do.
> The new lock needs to be added to the table in monitoring.sgml.
Same.
> I don't think the new header comments in TransactionIdDidCommit and
> TransactionIdDidAbort are super-clear. I'm not sure you're going to
> be able to explain it there in a reasonable number of words, but I
> think that speaking of "testing against oldestClogXid" will leave
> people wondering what exactly that means. Maybe just write "caller is
> responsible for ensuring that the clog records covering XID being
> looked up can't be truncated away while the lookup is in progress",
> and then leave the bit about CLogTruncationLock to be explained by the
> callers that do that. Or you could drop these comments entirely.
OK. I'll revisit and see if I can clean it up, otherwise remove it.
> Overall, though, I think that 0001 looks far better than any previous
> iteration. It's simple. It looks safe. It seems unlikely to break
> anything that works now. Woo hoo!
Funny that this started with "hey, here's a simple, non-invasive
function for looking up the status of an arbitrary xid".
Mature, complex systems eh?
-- Craig Ringer http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services
