Re: MVCC snapshot timing

On Tue, Nov 12, 2013 at 03:36:01PM -0800, David Johnston wrote:
> Bruce Momjian wrote
> > We just want to get across the MVCC concept in the intro --- we cover
> > the snapshots later in the document.
>
> I just think we're being too vague here; and we are covering them in the
> intro with the use of "some point in the past".
>
> IMO, the main point regarding MVCC is that every change in the system
> creates a new record and causes a prior record to be invalidated at a
> point-in-time.  The combination of these two things increases concurrency
> since you can create new records while people are still using the old ones.
> One consequence, though, is that it is necessary for the user to decide at
> what point in the timeline they want to view the database.
>
> Does this sound right?

I still do not see how this fits appropriately in the introduction.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +