On 7/3/2007 12:33 PM, Christopher Browne wrote:
> "Andrew Hammond" <andrew.george.hammond at gmail.com> writes:

>> Also, ISTM that the big reason we don't like statement based
>> replication is that SQL has many non-deterministic aspects. However,
>> there is probably a pretty darn big subset of SQL which is provably
>> non-deterministic. And for that subset, would it be any less
>> rigorous to transmit those statements than to transmit the per-row
>> change statments like we currently do?
> 
> Well, by capturing the values, we have captured a deterministic form
> of the update.

How to figure out what is deterministic and what isn't? A simple

     insert into summary select id, sum(value) from detail group by id;

seems pretty deterministic, doesn't it? But the result of it depends on 
the exact commit order and the transaction isolation level. We don't 
capture the commit order of single transactions, nor do we care for it 
anywhere in the Slony-I logic.


Jan

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