Re: [Koha-zebra] A few Zebra Questions

[Sebastian Hammer]

Mike Taylor wrote:

> > Date: Thu, 29 Dec 2005 15:55:10 -0500
> > From: Sebastian Hammer <address@hidden>
> >
> >    
> >
> > > Does Zebra allow any kind of database replication, master/slave or
> > > master/master relationships? (or alternatively, are there methods
> > > to communicate between two or more Zebra servers?)
> > >      
> > Oooh.. serious dream project. I have fantasized about this for
> > years.  But no, there is nothing built into Zebra today.
> >
> > One somewhat obvious way to approach this would be using
> > OAI-PMH.. the LoC is presently contemplating awarding us a little
> > money to support an OAI server function in Zebra.
> >    
>
> Why?!  What on earth does OAI-PMH bring to the party that Zebra
> doesn't already support natively through Z39.50 and/or SRU?  For
> example to search for records updated since 15th December:
>
>         rec.lastModificationDate >= 2005-12-15
>  
I'm not always hip to the latest changes to Zebra, but last I looked, it 
didn't support searching by record update timestamp. The other thing 
missing is the ability to retrieve information about records that have 
been deleted. At present, these just disappear without a trace.. there 
needs to be some mechanism to retrieve information (at least a sysno) 
about records deleted since a given date.

Whether the updating happens through OAI (which has only the benefit of 
being specifically made for this purpose) or SRU (Rob Sanderson and 
Ralph Levan have put forward a SRU profile to support OAI-like 
activities -- don't recall if they deal with delete records, though) 
doesn't matter much in the great scheme of things.. except when you 
follow standards, there is always a hope that other standards-compliant 
software will interoperate with you.

> It would be the work of a moment to set up a periodic polling daemon
> that use a query such as this to check for changes to a master Zebra
> database and propagates them to a slave.
>
>  
>
> > > Is there any foreseeable way to get around the speed issues with
> > > updating that would make it feasible to store status data quickly?
> > >      
> > What is the issue here -- the ability to use circulation status as a
> > filter in bibliographic searching, or what?
> >    
>
> Another question that immediately occurs is: _what_ speed issues?
> Have you actually seen any?  Do you have any numbers?
>  
I'd like to hear the answer to this too. But my sense is that updating a 
single record in a multimillion record database does take some 
significant period of a time -- much more than updating a single row in 
an RDBMS, for sure. It matters if you're scaling to a major library with 
multiple circulation desks.

--Sebastian

> _/|_     ___________________________________________________________________
> /o ) \/  Mike Taylor  <address@hidden>  http://www.miketaylor.org.uk
> )_v__/\  "Press any key to continue or any other key to quit" -- Jeff
>          Covey.
>
>
>  

--
Sebastian Hammer, Index Data
address@hidden   www.indexdata.com
Ph: (603) 209-6853