Re: Re: [COMMITTERS] pgsql: Efficient transaction-controlled synchronous replication.

On 03/07/2011 10:46 AM, Heikki Linnakangas wrote:
> On 07.03.2011 17:03, Andrew Dunstan wrote:
>> This is about expectations. The thing that worries me is that the use of
>> this term might cause some people NOT to use 2PC because they think they
>> are getting an equivalent guarantee, when in fact they are not. And
>> that's hardly unreasonable. Here for example is what wikipedia says
>> <http://en.wikipedia.org/wiki/Replication_%28computer_science%29>:
>>
>> Synchronous replication - guarantees "zero data loss" by the means
>> of atomic write operation, i.e. write either completes on both sides
>> or not at all. Write is not considered complete until
>> acknowledgement by both local and remote storage.
>
> Hmm, I've read that wikipedia definition before, but the "atomic" part
> never caught my eye. You do get zero data loss with what we have; if a
> meteor strikes the master, no acknowledged transaction is lost. I find
> that definition a bit confusing.

Maybe it is - I agree the difference might be small. I'm just trying to
make sure we don't use a term that could mislead reasonable people about
what we're providing. If we're satisfied that we aren't, then keep it.

cheers

andrew