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From Duncan Groenewald <dagroenew...@optusnet.com.au>
Subject Re: Derby Transaction Log Shipping
Date Thu, 07 Feb 2008 22:57:25 GMT
Thanks - the specification looks like its close to what I would  
like.  The model I work from is one used by Sybase (and possibly  
others) where you can specify a database dump and a separate  
transaction log dump at defined intervals using a script or some  
other programmatic method.  From what I can tell its not possible to  
do this with Derby, since you can only dump the database and not the  
logs.  Its also unclear how you would load a log file on its own.

What I would like to see is two additional commands added to dump  
transaction logs to specified directory or file name and another  
command to load a transaction log file from a specified location/ 
file.  Ideally a transaction log file load should function much the  
same way a normal user does to allow concurrent user access while  
loading a transaction log file.

I would be interested what people think about this approach and  
whether there is any way of adding transaction log dump commands  
without major rewrite of the derby architecture !!


On 08/02/2008, at 2:04 AM, Jørgen Løland wrote:

> Duncan Groenewald wrote:
>> Hi, does anyone know if it is possible to get some kind of log  
>> shipping working with Derby such that it is possible to create a  
>> second database instance that runs and periodically loads  
>> transaction log dumps from the primary database ?
>> Is it even possible to load a transaction log while a database is  
>> running ?
>> Basically I want to have a second copy of the database running in  
>> read only mode but still reasonably up to date, say every 15 minutes.
>> Thanks
>> Duncan Groenewald
>> mobile: +61406291205
>> email: dagroenewald@optusnet.com.au
> Hi Duncan,
> There is currently no such feature in Derby, but the next release  
> will include asynchronous replication based on log shipping from a  
> master version to a slave version of the database. However, the  
> first version of replication will not allow read operations on the  
> slave database.
> Take a look at the functional specification for replication on this  
> page: https://issues.apache.org/jira/browse/DERBY-2872
> If what is described there suits your needs, you'll find this  
> functionality in the next release of Derby (ETA in a few months).  
> If a read-only second copy of the database is what you really need,  
> I think you will have to hack something together using scripts  
> outside Derby for now. I think I can guide you through that, but it  
> *will* be pretty messy and I have not tried it myself. Please let  
> me know :)
> Hope this helps
> -- 
> Jørgen Løland

Duncan Groenewald
mobile: +61406291205
email: dagroenewald@optusnet.com.au

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