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DB2 replication

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Deacon

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Mar 2, 2003, 10:15:21 AM3/2/03
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Dear all,

I have some silly questions but not sure what the answer is :

1. I have two database. I use DB2 replication to synchronise the table
within the two database. Suppose the same tables will be updated
individually on both side. Is the DB2 replicator still can sychronise the
tables ?


2. If I set the table to be replicate in bi-direction, when I update table
A, the change will be apply to Table B. But when the change is apply to B,
will this changes be captured by B again and then replicate back to A (ie.
become a loop) ?

Table A (machine A) <------ replication -------> Table B (machine B).


Thanks !

Deacon

larry

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Mar 2, 2003, 12:01:59 PM3/2/03
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Deacon,

Your issues here can be addressed by using "Replica" support in DB2
Replication. See the DB2 Replication Guide. In short, the replica support can
be set up to detect and resolve conflicts, in accordance with a "master/slave"
hierarchy. Conflict resolution means backing out any records already applied,
so it is to be used with care for performance reasons (especially across a
network with many replica copies of the same table). If that you have this
kind of scenario, you are much better off designing to isolate the data
(perhaps using views) so that conflicts cannot occur.

Take a look at http://www-3.ibm.com/software/data/dpropr/whitepaperspres.html.
There is a very old (but very good) white paper there named "Update
Replication: What Every Designer Should Know ". You may find the other
material of some use also.

Larry Edelstein

Knut Stolze

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Mar 3, 2003, 2:22:34 AM3/3/03
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Deacon wrote on Sunday 02 March 2003 16:15:

> Dear all,
>
> I have some silly questions but not sure what the answer is :
>
> 1. I have two database. I use DB2 replication to synchronise the table
> within the two database. Suppose the same tables will be updated
> individually on both side. Is the DB2 replicator still can sychronise the
> tables ?

Yes.

> 2. If I set the table to be replicate in bi-direction, when I update table
> A, the change will be apply to Table B. But when the change is apply to B,
> will this changes be captured by B again and then replicate back to A (ie.
> become a loop) ?

No, circular dependencies are detected and prevented.

--
Knut Stolze
Information Integration
IBM Germany / University of Jena

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