Re: Overhead cost of Serializable Snapshot Isolation

Simon Riggs <simon@2ndQuadrant.com> wrote:
> Greg Sabino Mullane <greg@endpoint.com> wrote:
>> Eh? It has an off switch: repeatable read.
> 
> You mean: if we recode the application and retest it, we can get
> it to work same way as it used to.
> 
> To most people that is the same thing as "it doesn't work with
> this release", ask any application vendor.
> 
> There is no off switch and there should be.
This was discussed at some length, and nobody seemed to favor a
behavior-changing GUC.  One example of such a thread is here:
http://archives.postgresql.org/pgsql-hackers/2009-05/msg01165.php
It came up at least a couple other times, and the outcome was always
the same -- after discussion, nobody was in favor of a GUC to make
the semantics of these statement variable.  I'm sorry if you missed
those discussions.  It would certainly be a trivial change to
implement; the problem is convincing others that it's a good idea.
-Kevin