Re: Overhead cost of Serializable Snapshot Isolation

On Oct11, 2011, at 23:35 , Simon Riggs wrote:
> On Tue, Oct 11, 2011 at 10:30 PM, Florian Pflug <fgp@phlo.org> wrote:
>
>> That experience has taught me that backwards compatibility, while very
>> important in a lot of cases, has the potential to do just as much harm
>> if overdone.
>
> Agreed. Does my suggestion represent overdoing it? I ask for balance,
> not an extreme.

It's my belief that an "off" switch for true serializability is overdoing
it, yes.

With such a switch, every application that relies on true serializability for
correctness would be prone to silent data corruption should the switch ever
get set to "off" accidentally.

Without such a switch, OTOH, all that will happen are a few more aborts due to
serialization errors in application who request SERIALIZABLE when they really
only need REPEATABLE READ. Which, in the worst case, is a performance issue,
but never an issue of correctness.

best regards,
Florian Pflug