From: | "Greg Sabino Mullane" <greg(at)turnstep(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Bidirectional replication |
Date: | 2011-05-09 02:44:24 |
Message-ID: | 6b0d9077ef48637b9fab55d968c7f8f7@biglumber.com |
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Lists: | pgsql-general |
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> Yeah. One nasty property that async multi master solutions share is
> that they change the definition of what 'COMMIT' means -- the database
> can't guarantee the transaction is valid because not all the
> supporting facts are necessarily known. Even after libpq gives you
> the green light that transaction could fail an arbitrary length of
> time later, and you can't rely in the assumption it's valid until
> you've done some synchronizing with the other 'masters'. Maybe you
> don't need to rely on that assumption so a 'fix it later, or possibly
> never' methodology works well. Those cases unfortunately fairly rare
> in the real world.
I don't quite follow you here. Are you talking about *synchronous* multi-master?
Async multi-master works just fine, as long as you are not expecting the
servers to give the exact same answer at the exact same time. But certainly
transactions are "valid".
- --
Greg Sabino Mullane greg(at)turnstep(dot)com
End Point Corporation http://www.endpoint.com/
PGP Key: 0x14964AC8 201105082243
http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8
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