On Fri, 11 Nov 2005, Josh Berkus wrote: > Jaime, > > > why? seems that REPLACE only work if there are at least one row > > matching... > > Scenario: > > session1: REPLACE .... 1 > session2: REPLACE ..... 1 > session1: check to see that "1" exists .... no > session2: check to see that "1" exists .... no > session1: INSERT 1 > session2: INSERT 1 .... ERROR > > Get the picture? The only way to avoid a race condition is to be able to > do "predicate locking", that is to lock the table against any data write > matching that predicate.
When it comes to predicate locking, I think we should defer to Peter's comment at Open DB Con: http://www.treehou.se/~swm/peter_merge.jpg Gavin ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
