sql server replication: Subscriber Reinitialization and Retention Period -- sql server replication

You're in the

sql server replication

group:

Subscriber Reinitialization and Retention Period

Maer
7/31/2004 2:34:53 PM

sql server replication:

Hi Guys - I am trying to understand how merge replication works. One
question that I have is this: after the intial snapshot is applied to the
subscriber, does the Snapshot Agent at the publisher generate a new snapshot
every time the Merge Agent runs (although it may not apply it to the
subscrobers)? Or does it create the snapshot only when the publisher
reinitializes?

Along the same lines, is there a rule of thumb on how often subscribers
should be reinitialized? What are the benefits?

Another question is about the retention period. The default is 14 days
for merge replication. What are the negative affects of setting
subscriptions to never expire?

Thank you - Maer

Re: Subscriber Reinitialization and Retention Period

Paul Ibison
8/1/2004 11:47:24 AM

Maer,

on initialization, the merge agent will look for the snapshot files. If they
are not there, the merge agent will not automatically start the snapshot
agent.

Reinitialization of subscribers is required when the articles in the
publication need changing in a way that is not possible with replication set
up, or if there is non-convergence of data (failure of data validation etc).
In a typical setup, reinitialization is never really necessary.

The retention period of 14 days prevents old subscriber data from
synchronizing and uploading these changes to the Publisher. It also helps
optimize replication with the metadatacleanup, so setting it to never expire
is not generally a good idea.

HTH,

Paul Ibison

Re: Subscriber Reinitialization and Retention Period

Maer
8/1/2004 11:50:41 AM

Thank you, Paul. It makes sense to me now. I will also look into
metadatacleanup so I am more informed.

So, what happens to the old expired subscriber? If they made changes to
their replica, would they be just out of luck and not be able to sync
anymore? Would they have to unsubscribe and subscribe again? What would be
the most logical course of action in this scenario?

Thanks again for your time and insight,

Maer

[quoted text, click to view]

Re: Subscriber Reinitialization and Retention Period

Paul Ibison
8/2/2004 8:31:05 AM

Maer,

have a look at "expired subscriptions" in BOL - the bottom section describes
merge deactivation behaviour.

If the merge subscription is not cleaned up and the subscriber continues to
make changes, on reinitialization you can choose to have all the data
changes uploaded from the Subscriber before the snapshot is reapplied. Any
updates that have been made at the Subscriber since the last synchronization
will be propagated to the Publisher before the snapshot is reapplied.

HTH,

Paul Ibison

Re: Subscriber Reinitialization and Retention Period

Hilary Cotter
8/2/2004 8:32:06 AM

Depending on the size of your snapshot, reinitializing can improve
performance as it clears the MSMerge_contents and MSMerge_tombstone tables.

--
Hilary Cotter
Looking for a book on SQL Server replication?
http://www.nwsu.com/0974973602.html

[quoted text, click to view]

Got something to say? Click here to post a reply to this thread.

Don't see what you're looking for? Try a search.

View other messages in the sql server replication group.

View Other Months
April 2003
June 2003
July 2003
August 2003
September 2003
October 2003
November 2003
December 2003
January 2004
February 2004
March 2004
April 2004
May 2004
June 2004
July 2004
August 2004
September 2004
October 2004
November 2004
December 2004
January 2005
February 2005
March 2005
April 2005
May 2005
June 2005
July 2005
August 2005
September 2005
October 2005
November 2005
December 2005
January 2006
February 2006
March 2006
April 2006
May 2006
June 2006
July 2006
August 2006
September 2006
October 2006
November 2006
December 2006
January 2007
February 2007
March 2007
April 2007
May 2007
June 2007
July 2007
August 2007
September 2007
October 2007
November 2007

home · blog · groups

Questions? Comments? Contact the dn