FIX: Users Can Control the Compensating Change Process in Merge Replication (828637)

SYMPTOMS

When you use merge replication, the Merge Agent may experience synchronization errors if an insert change, an update change, or a delete change cannot be applied at a destination replica for various reasons, including a primary key violation at the publisher or at the subscriber. The Merge Agent always sends a compensating change to the source replica to undo the failed change. The Merge Agent executes the compensating change process to make sure that data is maintained in a consistent and convergent state at all replicas. Without the compensating changes, data may vary between replicas if an error such as a primary key violation occurs. If the data varies across replicas, non-convergence of data occurs.

Before this hotfix, there was no way to permit users to control the compensating change process. The compensating change process was handled internally by the Merge Agent. Because this process was handled internally by the Merge Agent, it was difficult to troubleshoot why certain conflicts occurred. Also, because the conflicting row is deleted from or undone in all the replicas, the row data is removed from the whole topology. To help troubleshoot these issues, Microsoft has added a new article-level property to merge replication that permits users to control the compensating change process.

RESOLUTION

Service pack information

To resolve this problem, obtain the latest service pack for Microsoft SQL Server 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

290211 How to obtain the latest SQL Server 2000 service pack

Hotfix information

The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

   Date         Time   Version            Size    File name
   ----------------------------------------------------------------------
   31-May-2003  18:45  2000.80.818.0      78,400  Console.exe      
   25-Jun-2003  01:01  2000.80.818.0      33,340  Dbmslpcn.dll     
   25-Apr-2003  02:12                    786,432  Distmdl.ldf
   25-Apr-2003  02:12                  2,359,296  Distmdl.mdf
   30-Jan-2003  01:55                        180  Drop_repl_hotfix.sql
   26-Aug-2003  20:16  2000.80.854.0     528,960  Dtspump.dll      
   23-Jun-2003  22:40  2000.80.837.0   1,557,052  Dtsui.dll        
   23-Jun-2003  22:40  2000.80.837.0     639,552  Dtswiz.dll       
   24-Apr-2003  02:51                    747,927  Instdist.sql
   03-May-2003  01:56                      1,581  Inst_repl_hotfix.sql
   08-Feb-2003  06:40  2000.80.765.0      90,692  Msgprox.dll      
   01-Apr-2003  02:07                      1,873  Odsole.sql
   05-Apr-2003  01:46  2000.80.800.0      62,024  Odsole70.dll     
   07-May-2003  20:41  2000.80.819.0      25,144  Opends60.dll     
   02-Apr-2003  21:48  2000.80.796.0      57,904  Osql.exe         
   02-Apr-2003  23:15  2000.80.797.0     279,104  Pfutil80.dll     
   04-Aug-2003  18:17                    550,780  Procsyst.sql
   22-May-2003  22:57                     19,195  Qfe469571.sql
   06-Sep-2003  01:36                  1,090,932  Replmerg.sql
   06-Sep-2003  07:18  2000.80.858.0     221,768  Replprov.dll     
   06-Sep-2003  07:18  2000.80.858.0     307,784  Replrec.dll      
   06-Sep-2003  00:00                  1,087,150  Replsys.sql
   13-Aug-2003  16:28                    986,603  Repltran.sql
   29-Jul-2003  20:13  2000.80.819.0     492,096  Semobj.dll       
   31-May-2003  18:27  2000.80.818.0     172,032  Semobj.rll
   05-Aug-2003  21:06                    127,884  Sp3_serv_uni.sql
   01-Jun-2003  01:01  2000.80.818.0   4,215,360  Sqldmo.dll       
   07-Apr-2003  17:44                     25,172  Sqldumper.exe    
   19-Mar-2003  18:20  2000.80.789.0      28,672  Sqlevn70.rll
   02-Jul-2003  00:18  2000.80.834.0     180,736  Sqlmap70.dll     
   03-Sep-2003  02:56  2000.80.857.0     188,992  Sqlmmc.dll       
   02-Sep-2003  23:03  2000.80.857.0     479,232  Sqlmmc.rll
   08-Feb-2003  06:40  2000.80.765.0      57,920  Sqlrepss.dll     
   06-Sep-2003  07:19  2000.80.858.0   7,598,161  Sqlservr.exe     
   25-Jul-2003  21:44  2000.80.845.0     590,396  Sqlsort.dll      
   08-Feb-2003  06:40  2000.80.765.0      45,644  Sqlvdi.dll       
   25-Jun-2003  01:01  2000.80.818.0      33,340  Ssmslpcn.dll     
   01-Jun-2003  01:01  2000.80.818.0      82,492  Ssnetlib.dll     
   01-Jun-2003  01:01  2000.80.818.0      25,148  Ssnmpn70.dll     
   01-Jun-2003  01:01  2000.80.818.0     158,240  Svrnetcn.dll     
   31-May-2003  18:59  2000.80.818.0      76,416  Svrnetcn.exe     
   30-Apr-2003  23:52  2000.80.816.0      45,132  Ums.dll          
   02-Jul-2003  00:19  2000.80.834.0      98,816  Xpweb70.dll

Note Because of file dependencies, the most recent hotfix or feature that contains these files may also contain additional files.

MORE INFORMATION

This hotfix adds a new article-level compensate_for_errors property for merge publications. You can set this property to true or false. The default value for this property is true. The default setting means that merge replication continues to issue compensating changes as it has in all previous releases and service packs. When this property is set to true and an insert change, an update change, or a delete change cannot be applied at a destination replica for various reasons (a primary key violation occurs at either the publisher or the subscriber, for example), the Merge Agent sends a compensating change to the source replica to undo the change.

When the compensate_for_errors property is set to false and a change cannot be applied at a destination replica, compensating actions are not issued and the failed change remains as a conflict until the database administrator resolves the error condition. The Merge Agent tries to replicate the row on each subsequent synchronization run until the error condition is resolved.

Downlevel subscription agents, particularly pull subscribers that do not have this hotfix installed, continue to behave as though the compensate_for_errors property is set to true, even if you have installed this hotfix on the publisher and the compensate_for_errors property is set to false on the publisher. Therefore, users should upgrade all subscribers to this hotfix if they want to use the functionality that is provided by the new compensate_for_errors property. This upgrade helps to ensure consistent behavior across the topology.

For Microsoft SQL Server 2000 Windows CE Edition subscribers, download conflicts behave the same as in all previous SQL Server releases, regardless of the compensate_for_errors property setting. However, the setting of the compensate_for_errors property determines whether compensating changes are generated during the upload of errors and conflicts from SQL Server CE subscribers to a SQL Server publisher (when both the publisher and the computer that is running Microsoft Internet Information Services (IIS) have been upgraded to this hotfix).

This property is exposed in both the sp_addmergearticle stored procedure and the sp_changemergearticle stored procedure as a new parameter named @compensate_for_errors. This property is not exposed in SQL Server Enterprise Manager. This property can be changed for existing articles without being reinitialized. The typical use of this property is:

exec sp_addmergearticle @publication = N'mypubl1', @article = N'authors', @source_owner = N'dbo', @source_object = N'authors', @compensate_for_errors='false'
or
exec sp_changemergearticle  @publication='mypubl1',@article='authors', @property='compensate_for_errors',@value='false'

Additions to the "sp_addmergearticle" Topic in SQL Server 2000 Books Online

sp_addmergearticle [@compensate_for_errors = ]
		  'compensate_for_errors'

The compensate_for_errors property controls whether the compensating actions are taken when errors are encountered during synchronization. The @compensate_for_errors parameter is defined as nvarchar(5) and has a default setting of true. By default, a change that cannot be applied at a subscriber or at a publisher during synchronization always leads to compensating actions to reverse the change. However, one incorrectly configured subscriber that generates an error can cause changes at other subscribers and publishers to be incorrectly reversed. Setting the compensate_for_errors property to false disables these compensating actions.

Note Setting the compensate_for_errors property to false may cause non-convergence.

Additions to the "sp_changemergearticle" Topic in SQL Server Books Online


sp_changemergearticle [ @publication = ] 'publication' , [ @article = ] 'article' [ , [
		  @property = ] 'property' ] [ , [ @value =] 'value' ]

Property	Values	Description
compensate_for_errors	True	Compensating actions are performed when errors occur during synchronization. This is the default behavior.
compensate_for_errors	False	Compensating actions are not performed

Note Setting the compensate_for_errors property to false may cause non-convergence.

The following select statement determines whether the compensate_for_errors property is set to true or false:

select CASE compensate_for_errors WHEN 0 THEN 'FALSE' ELSE 'TRUE' END from sysmergearticles where name = 'NameOfTheArticle'

Because the compensate_for_errors property is a shared property for a particular article, its value should to be consistent if the article belongs to multiple publications (such as with republisher scenarios and alternative synchronization partners). This condition is enforced most of the time. However, it is the user's responsibility to make sure that the compensate_for_errors property has the same value for a particular article in all the publications that share the article. Again, this ensures consistent behavior across the topology.

Note If you have to restore a backup of a replicated database that was backed up before this hotfix was applied to the instance of SQL Server, run the sp_vupgrade_replication stored procedure with the required parameters against the instance of SQL Server to use the restored database in replication.

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the Standard Terminology That Is Used to Describe Microsoft Software Updates