FIX: The synchronization operation of a merge replication times out in Microsoft SQL Server 2005

Applies to: Microsoft SQL Server 2005 Standard EditionMicrosoft SQL Server 2005 Developer EditionMicrosoft SQL Server 2005 Enterprise Edition

Bug #: 50002786 (SQL Hotfix)
Microsoft distributes Microsoft SQL Server 2005 fixes as one downloadable file. Because the fixes are cumulative, each new release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2005 fix release.

Symptoms


Consider the following scenario. In Microsoft SQL Server 2005, you configure a merge replication. Then, you deploy the snapshot to a subscriber. In this scenario, when you run the Merge Agent to synchronize data, the operation times out when the Merge Agent calls the sp_MSmakegeneration stored procedure.

Additionally, when you run the following statement against the replicated database of the subscriber after the operation times out, the query returns some records that are susceptible to the issue:
select * from dbo.MSmerge_genhistory gh 
where not exists
(select * from dbo.MSmerge_contents as mc
where mc.generation = gh.generation)
and not exists
(select * from dbo.MSmerge_tombstone as ts
where ts.generation = gh.generation)
and genstatus = 0
union
select * from dbo.MSmerge_genhistory gh
where exists
(select * from dbo.MSmerge_contents as mc
where mc.generation = gh.generation
and mc.tablenick <> gh.art_nick)
or exists
(select * from dbo.MSmerge_tombstone as ts
where ts.generation = gh.generation
and ts.tablenick <> gh.art_nick)
and genstatus = 0

Cause


This issue occurs because there is a row in the MSmerge_genhistory table that meets one of the following conditions:
  • The generation has no changes that are mapped to it in the MSmerge_tombstone table or in the MSmerge_contents table.
  • One or more rows that are mapped to the generation have an incorrect value in the tablenick column in the MSmerge_tombstone table or in the MSmerge_contents table.
This situation causes the sp_MSmakegeneration stored procedure to go into an infinite loop.

Resolution


The fix for this issue was first released in Cumulative Update 8. For more information about how to obtain this cumulative update package for SQL Server 2005 Service Pack 2, click the following article number to view the article in the Microsoft Knowledge Base:
951217 Cumulative update package 8 for SQL Server 2005 Service Pack 2
Note Because the builds are cumulative, each new fix release contains all the hotfixes and all the security fixes that were included with the previous SQL Server 2005 fix release. Microsoft recommends that you consider applying the most recent fix release that contains this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
937137 The SQL Server 2005 builds that were released after SQL Server 2005 Service Pack 2 was released
Microsoft SQL Server 2005 hotfixes are created for specific SQL Server service packs. You must apply a SQL Server 2005 Service Pack 2 hotfix to an installation of SQL Server 2005 Service Pack 2. By default, any hotfix that is provided in a SQL Server service pack is included in the next SQL Server service pack.

Workaround


To work around this issue, follow these steps:
  1. Cancel the synchronization operation that is not completed.
  2. Run the following statements to obtain the generation_leveling_threshold setting for the publication:
    use <Publication Database Name>
    go
    exec sp_helpmergepublication @publication = '<Publication Name>'
    Note the value of the generation_leveling_threshold setting.
  3. Run the following statements to disable generation leveling and generation coalescing:
    use <Publication Database Name>
    exec sp_changemergepublication @publication = '<Publication Name>'
    , @property = 'generation_leveling_threshold'
    , @value = 0
  4. Synchronize data for the publication.
  5. After the synchronization is completed successfully, reset the generation_leveling_threshold setting back to the value that you noted in step 2. To do this, run the following statements:
    use <Publication Database Name>
    exec sp_changemergepublication @publication = '<Publication Name>'
    , @property = 'generation_leveling_threshold'
    , @value = <Value>
After you use this method to work around this issue, this issue will occur again if another subscriber tries to process the generation. You must repeat these steps for all subscribers who encounter the problem.

Status


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information


For more information about what files are changed, and for information about any prerequisites to apply the cumulative update package that contains the hotfix that is described in this Microsoft Knowledge Base article, click the following article number to view the article in the Microsoft Knowledge Base:
951217 Cumulative update package 8 for SQL Server 2005 Service Pack 2

References


For more information about the list of builds that are available after SQL Server Service Pack 2, click the following article number to view the article in the Microsoft Knowledge Base:
937137 The SQL Server 2005 builds that were released after SQL Server 2005 Service Pack 2 was released
For more information about the Incremental Servicing Model for SQL Server, click the following article number to view the article in the Microsoft Knowledge Base:
935897 An Incremental Servicing Model is available from the SQL Server team to deliver hotfixes for reported problems
For more information about how to obtain SQL Server 2005 Service Pack 2, click the following article number to view the article in the Microsoft Knowledge Base:
913089 How to obtain the latest service pack for SQL Server 2005
For more information about the new features and the improvements in SQL Server 2005 Service Pack 2, visit the following Microsoft Web site: For more information about the naming schema for SQL Server updates, click the following article number to view the article in the Microsoft Knowledge Base:
822499 New naming schema for Microsoft SQL Server software update packages
For more information about software update terminology, 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