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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Monday, July 21, 2008 12:42 PM
To: [email protected]
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
