Re: Reviewers Guide to DeferredTransactions/TransactionGuarantee

On Sun, 2007-04-08 at 11:05 -0400, Tom Lane wrote:
> "Simon Riggs" <simon@2ndquadrant.com> writes:
> >> 4. The recent changes to remove CheckpointStartLock haven't changed the
> >> code path for deferred transactions, so a similar solution might be
> >> possible there also.
>
> > Some further discussion required here, I think. That change may actually
> > have introduced a slight risk into the patch. Will raise at review.
>
> Given that you're going to be gone for the next two weeks, I'm wondering
> when you think that discussion will happen.

Well, now is good... but I would never say "this must happen now".

I'm sorry my schedule is busy at this time, I really thought the change
of dates would mean I'd avoid my normal disappearing trick. Previously
its been family holidays, now its just other business I am called to.


My concern was this:

If we flush the currently outstanding deferred transactions then that
doesn't guarantee they have all reached the clog. Previously, a deferred
transaction would not release the CheckpointStartLock until after the
clog had been updated.

If we wait for all currently inCommit transactions to end this will
cover all deferred transactions also. So I think I just need to flush
deferred transactions prior to the wait and this will be valid. Would
you agree?

--
  Simon Riggs
  EnterpriseDB   http://www.enterprisedb.com