Re: INSERT...ON DUPLICATE KEY LOCK FOR UPDATE

On Mon, Feb 10, 2014 at 06:40:30PM +0000, Peter Geoghegan wrote:
> On Sun, Jan 19, 2014 at 2:17 AM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
> > I'm just throwing an error when locking the tuple returns
> > HeapTupleInvisible, and the xmin of the tuple is our xid.
>
> I would like some feedback on this point. We need to consider how
> exactly to avoid updating the same tuple inserted by our command.
> Updating a tuple we inserted cannot be allowed to happen, not least
> because to do so causes livelock.
>
> A related consideration that I raised in mid to late January that
> hasn't been commented on is avoiding updating the same tuple twice,
> and where we come down on that with respect to where our
> responsibility to the user starts and ends. For example, SQL MERGE
> officially forbids this, but MySQL's INSERT...ON DUPLICATE KEY UPDATE
> seems not to, probably due to implementation considerations.

Where are we on this?

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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