Re: INSERT...ON DUPLICATE KEY IGNORE

On 09/03/2013 06:18 AM, Peter Geoghegan wrote:
> On Mon, Sep 2, 2013 at 6:25 AM, Craig Ringer <craig@2ndquadrant.com> wrote:
>> It'll be yet another way for people to get upsert wrong, of course.
>> They'll use a wCTE with RETURNING REJECTS to do an UPDATE of the rejects
>> w/o locking the table against writes first. Documenting this pitfall
>> should be enough, though.
> 
> My preferred solution is to actually provide a variant to lock the
> rows implicated in the would-be unique constraint violation. Obviously
> that's a harder problem to solve.

That'd certainly be the ideal, but as you say is far from simple, and
IIRC prior discussions here have suggested the SSI / predicate locking
stuff won't help.

-- Craig Ringer                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services