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From V Narayanan <V.Naraya...@Sun.COM>
Subject Re: Replication
Date Tue, 22 Jul 2008 06:04:37 GMT
Hi Mike,

Currently the replication functionality is not a pluggable module but is 
rather strongly linked with the store
layer. For example LogToFile has been actually modified to catch the log 
records and store them in the log
buffer in addition to storing them on the master. If you are thinking 
about implementing a synchronous or
a synchronous (but read-only masters, I think in this case also you 
would be constrained to commit a transaction
only after all the masters sync), you would do great to think of how 
this can be implemented as a separate module
rather than coupling it tightly with the store as is happening now.

You could also think about convincing the community about the advantages 
a synchronous replication scheme might
bring to Derby over the existing asynchronous scheme and probably think 
about modifying existing implementation
to work in a sychronous way, or atleast think about how the existing 
functionality can be bundled as a separate unit.

Some good places to start would be

http://issues.apache.org/jira/browse/Derby-2872

http://wiki.apache.org/db-derby/ReplicationWriteup

You could also look at some synchronous replication products listed here

http://wiki.apache.org/db-derby/UsesOfDerby

looking at them would probably help you what type of an end product you 
would expect.

There was an effort from a student to provide hot standby functionality 
to derby, you can find the paper and related work here

https://issues.apache.org/jira/browse/DERBY-2852

I will help you in whatever way I can in this effort, but I may not 
actually be operation in synchronous mode ;) , I promise
asynchronous read-only, commit-maybe, support to your effort :) .

But your proposal looks interesting, please do remember to keep the 
community informed about your ideas, efforts and problems
constantly. I have noticed that the community appreciates continuous 
feedback on issues.

Narayanan
Mike Boom wrote:
> I may want to add master/master replication or at least master/readonly
> replication.  How would I find out who the original contributors would
> be?
>
> -----Original Message-----
> From: Richard.Hillegas@Sun.COM [mailto:Richard.Hillegas@Sun.COM] 
> Sent: Monday, July 21, 2008 12:42 PM
> To: derby-dev@db.apache.org
> Subject: Re: Replication
>
> Mike Boom wrote:
>   
>> I hope this is an appropriate place to ask this question. Is there a 
>> plan in the future for replication to provide readable replicas, or 
>> even better multiple masters?  If so what kind of time line are we 
>> looking at for completion?  Thanks.
>>
>>     
> Hi Mike,
>
> I have not seen a lot of work on replication recently, other than 
> stabilization of the existing functionality and tests. Probably, the 
> original contributors would be happy to coach someone who wanted to 
> extend Derby replication.
>
> Regards,
> -Rick
>
>   


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