Re: Parallell Optimizer

On 06/12/2013 07:01 AM, Tatsuo Ishii wrote:
>>>> Please explain what you mean by the word "true" used here.
>>> In another word, "eager replication".
>> Do you mean something along these lines :
>>
>> "Most synchronous or eager replication solutions do conflict prevention,
>> while asynchronous solutions have to do conflict resolution. For instance,
>> if a record is changed on two nodes simultaneously, an eager replication
>> system would detect the conflict before confirming the commit and abort
>> one of the transactions. A lazy replication system would allow both
>> transactions to commit and run a conflict resolution during
>> resynchronization. "
>>
>> ?
> 
> No, I'm not talking about conflict resolution.
> 
> From http://www.cs.cmu.edu/~natassa/courses/15-823/F02/papers/replication.pdf:
> ----------------------------------------------
> Eager or Lazy Replication?
>  Eager replication:
>  keep all replicas synchronized by updating all
>  replicas in a single transaction
> 
>  Lazy replication:
>  asynchronously propagate replica updates to
>  other nodes after replicating transaction commits
> ----------------------------------------------

OK, so you mean it's *globally* synchronous, perhaps using something
like 2PC. All replicas get the transaction and apply it or none do.

Right?

-- Craig Ringer                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services