> >-----Original Message----- > >From: Peter Brawley [mailto:peter.braw...@earthlink.net] > >Sent: Wednesday, August 31, 2011 10:40 AM > >To: r...@grib.nl; mysql@lists.mysql.com > >Subject: Re: locked non-existent row > > > >On 8/31/2011 4:50 AM, Rik Wasmus wrote: > >>> While a transaction in one thread tries to update a non-existent InnoDB > >>> row with a given key value, an attempt to insert that value in another > >>> thread is locked out. Does anyone know where this behaviour is > >>> documented? > > [JS] Forgive my ignorance, but I thought that was standard behavior for a > row- or row-range lock (not just MySQL) in any DBMS that supported row > locking. (Back when these things were first being invented, one term was > "predicate locking.") The general idea was that you are locking rows that > meet certain criteria, whether any or all of them exist or not. You're > locking not only the existence, but the potential existence, of those > rows. > > I would expect it to apply not only to keys, but to any set. For example, > > SELECT * FROM `t` WHERE `t`.`x` < 3 FOR UPDATE; > > should lock all rows where `t`.`x` < 3 for update, insertion, or deletion > -- regardless of whether or not `x` is a key. Otherwise you have no way of > knowing who wins. > > The ability to lock non-existent records is critical.
I concur, although this is just a transaction consisting of 1 statement :). -- Rik Wasmus -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
