Re: Can a deferred FK constraint cause "enq: TX - row lock contention" in Share (4) mode?

  • From: Thomas Kellerer <thomas.kellerer@xxxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Mon, 07 Jul 2014 07:51:48 +0200

Jonathan,

thanks for your answers. 

> One scenario I've created which matches one set of your symptoms:
> 
> Foreign key is deferrable initially deferred.
> Session 1 inserts a new parent key value - without commiting.
> Session 2 updates a child row changing a value that exists in the parent 
> table to the new, uncommitted, parent value.
> 
> Session 2 goes into TX mode 4 waiting for session 1 to commit; showing -1 as 
> the current_obj#

I will need to discuss with the developers how exactly the code deals with the 
inserts, but this will help a lot in that discussion. 
Maybe it's possible to do all the parent inserts first.

Regards
Thomas

--
//www.freelists.org/webpage/oracle-l


Other related posts: