[Bucardo-general] Swap replication latency
Alex Balashov
abalashov at evaristesys.com
Wed May 4 22:51:00 UTC 2011
On 05/04/2011 06:26 PM, Joshua Tolley wrote:
> On Wed, May 04, 2011 at 12:34:35PM -0400, Alex Balashov wrote:
>> How does Bucardo deal with this? I am realising just now that it may
>> not. Let's say I have table 'evariste_trans_events' on which a trigger
>> cascade operates to turn it into single 'evariste_trans' rows. The
>> normal way this happens on the source database is that the application
>> inserts rows into 'evariste_trans_events', and triggers machine that data
>> into the appropriate representation in 'evariste_trans' as needed. Most
>> of the time, 'evariste_trans' will be UPDATE'd based on subsequent
>> 'evariste_trans_events', although the initial event will cause an INSERT.
>
> Bucardo puts triggers on all replicated tables. When your application's
> triggers run and modify a replicated table, the bucardo triggers run and tag
> those rows for replication. On the slave, Bucardo disables application
> triggers, so it can replicate data from the master and not have your
> application's triggers getting in the way.
How does that work for swap, though, where data may be getting modified
via the same application triggers on the other master? This is not a
master->slave setup. It's just that right now, for testing purposes, I
only have the source master being written to.
--
Alex Balashov - Principal
Evariste Systems LLC
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