Re: Proposal for a cascaded master-slave replication system

On Tue, Nov 11, 2003 at 03:38:53PM -0500, Christopher Browne wrote:
> In the last exciting episode, JanWieck(at)Yahoo(dot)com (Jan Wieck) wrote:
> > I look forward to your comments.
>
> It is not evident from the paper what approach is taken to dealing
> with the duplicate key conflicts.
>
> The example:
>
> UPDATE table SET col1 = 'temp' where col = 'A';
> UPDATE table SET col1 = 'A' where col = 'B';
> UPDATE table SET col1 = 'B' where col = 'temp';

It's not a problem, because as the proposal states, the actual SQL is
to be sent in order to the slave. That is, only consistent sets are
sent: you can't have a condition on the slave that never could have
obtained on the master. This means greater overhead for cases where
the same row is altered repeatedly, but it's safe.

A

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