On Mon, 2010-12-06 at 15:25 -0500, Christopher Browne wrote:
> Steve Singer <ssinger at ca.afilias.info> writes:
> > On 10-12-04 01:38 PM, Simon Riggs wrote:
> >> On Fri, 2010-12-03 at 12:26 -0500, Christopher Browne wrote:
> >>> === Commit timestamps ===
> >>> * per Jan Wieck
> >>> * Requires PostgreSQL extension
> >>> * Eliminates need for periodic generation of SYNC events
> >>> * Simplifies queries for searching for sl_log_* data
> >>> * Enables carryover of commit times to subscribers
> >>
> >> It should be possible to do this using LISTEN/NOTIFY.
> >> Now we can pass a payload with the NOTIFY, we just need to pass the
> >> transaction id. That can be handled automatically by trigger.
> >
> > What happens if the server crashes before the process listening does
> > what it needs to?  I don't think the notification queue gets
> > persisted.
> 
> Not anymore, no, and that could well present a problem.

Yes, if server crashes, many things will be lost.

It seems likely to me that there will few, if any, transactions for
which we don't know the commit timestamp. All of the current
transactions will be lost.

Do we really need the timestamp for every single transaction? Surely we
can make a good guess from the transactions before and after.

-- 
 Simon Riggs           http://www.2ndQuadrant.com/books/
 PostgreSQL Development, 24x7 Support, Training and Services