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Home > Archive > Slony1 PostgreSQL Replication > September 2005 > ACID compliance
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| Nuno Fernandes 2005-09-16, 1:24 pm |
| Hi,
I'm testing slony and i have the following question. When an update comes to
PSQL master node, it is still ACID compliant (as it ought to be), right?
What about slave PSQLs? When slon ships the diferences to subscribes does it
send them in chunks of transactions? Are the slaves consistent at all times?
Imagine master node has an hardware failure and i failover the DB to slave
node. Does this one have to be checked for key constrains? I'm ok with some
data not being forwarded to slave node but the data in slave has to be
consistent. What procedure should be taken to ensure data integrity in the
slave node (even though it can loose some transactions)?
Thanks
Nuno Fernandes
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| Darcy Buskermolen 2005-09-16, 1:24 pm |
| On Friday 16 September 2005 10:47, Nuno Fernandes wrote:
> Hi,
>
> I'm testing slony and i have the following question. When an update comes
> to PSQL master node, it is still ACID compliant (as it ought to be), right?
> What about slave PSQLs? When slon ships the diferences to subscribes does
> it send them in chunks of transactions? Are the slaves consistent at all
> times?
Yes slony applys the transactions to the subscribers in their original
transactional group as well as order on a set by set bases.
>
> Imagine master node has an hardware failure and i failover the DB to slave
> node. Does this one have to be checked for key constrains? I'm ok with some
> data not being forwarded to slave node but the data in slave has to be
> consistent. What procedure should be taken to ensure data integrity in the
> slave node (even though it can loose some transactions)?
When ever possible use switchover as aposed to failover, the reasons for this
are documented. But yes the subscriber will be in a consistant state on a
set by set basis.
>
> Thanks
> Nuno Fernandes
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Darcy Buskermolen
Wavefire Technologies Corp.
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