Re: [Gnumed-devel] database replication with bucardo

[Karsten Hilbert]

On Wed, Jul 04, 2012 at 10:15:34PM +0000, Jim Busser wrote:

> Is the replicated record intended to exactly mirror every datum *except* the 
> pk which gets newly-assigned by the contextually-child system?
> 
> For example. suppose GNUmed was cloned via Bucardo at the point when GNUmed 
> had only 11 patients, and now in one system Kirk is created (being assigned 
> pk 12) at the same moment as -- in the other system -- some other "new 
> patient" is being created (also assigned pk = 12).
> 
> This results in two systems whose data content
> 
> - except for the pks, will always always the same
> 
> but pks will
> 
> - be different, in the situation of any latency (or lag-time or transient 
> disconnection) between syncs, during which there had been table alterations 
> at both ends
> 
> - at the end of a sync, achieve the same sequence number at both ends, with 
> the possibility of remaining the same (in sync) for those records which alter 
> a given table only at one end between syncs
> 
> and this is ok because one would never expect a cross-database search to have 
> meaning?

Bucardo needs to contain code to either mediate or prevent
such situations or else it is not fit for purpose.

Karsten
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