SQL Server Q&A

Symptoms
When you use transactional replication in a republishing topology, the Distribution Agent may experience an Access Violation (AV), which leads to an abnormal termination of the Distribution Agent.
When the Access Violation occurs on a server that is running Microsoft SQL Server 2000 Service Pack 2, the following stack dump is generated:

*******************************************************An exception was caughtin DISTRIB.EXE* Exception Address = 7800209a* Exception Code = c0000005********************************************************Module Name Return Address LocationMSVCRT 00403a45 wcsncpy + 14distrib 0040104c 00403a45distrib 77e8d326 0040104cKERNEL32 00000000 CreateProcessW + 900*******************************************************
Resolution
With transactional replication, the Logreader Agent invokes the sp_MSadd_replcommands27hp stored procedure to insert the log records from the publisher to the distribution database. The Distribution Agent then takes these log records and distributes them to the subscriber.
In a republishing topology, the sp_MSadd_replcommands27hp stored procedure may incorrectly insert an empty command (0x) in the MSRepl_commands system table in the distribution database. As a result, the Distributor Agent may experience the Access Violation mentioned in the “Symptoms” section when it tries to handle the empty command.
Logreader Agent
The Logreader might send a transaction with no command to distribution, with the intent being to update the MSrepl_transactions system table properly so that the next scan does not repeat the same section of the log.
The Distribution Agent does not expect an empty command; therefore, the Logreader checks the length of “command” in the sp_MSadd_repl_commands27hp stored procedure to make sure that the xact_seqno column is inserted in the MSRepl_transactions system table, but not in the MSRepl_commands system table.
The problem is that the “length checking” logic does not take into account a republishing or bi-directional scenario, where the originator srv and the db fields are not empty. It only checks to see if datalength(@data) > 39 to determine if the command is empty. However, it does not test the actual command data length(@cmd_data_len) before it inserts data in the MSRepl_commands system table.
Distribution Agent
The following data was gathered from the command that was causing the Access Violation:

xact_seqnotypearticle_id originator_id command_id commandcmd_data_len———————————- ———– ———- ————- ———- ————————-0×000770C1000000F6000100×00000000 NULL0×00000001 0×0 The Distribution Agent uses the sp_MSget_repl_commands stored procedure to select the commands that it needs to process. The sp_MSget_repl_commands stored procedure only picks up a command with article_id=0 when all of the following conditions are true: There are no inactive subscriptions.Loopback detection is not turned on for any articles.The number of articles in the MSsubscriptions system table is the same as the number of articles in the MSarticles system table for this particular publication. When the record with article_id=0 is picked up, the command (0x) is passed to the Distribution Agent; however, it is not handled gracefully and the Access Violation occurs.
To summarize, the cause of the problem is that:
The Logreader inserts a command of 0x in the MSRepl_commands system table in the distribution database. -and-
The Distribution Agent picks up commands with article_id=0 from the MSRepl_commands system table in the Distribution database.

Symptoms
In the Configure Publishing and Distribution Wizard, if you select the option to customize the settings rather than accept the default values, you are given the opportunity to change the distribution database name from its default of “distribution.” Although you cannot type a space character in the Distribution Database Name box, it does accept a space character if you copy a text string (for example, “my database”) to the clipboard and paste it in.
If the name you use contains a space character, the database is still created. However, if the name that you paste in begins with a space character (for example, ” my database”), the wizard fails with the following error message:

SQL Server Enterprise Manager could not configure ’server_name’ as the distributor for ’server_name’.
Error 14262: The specified @database_name (‘db_name’) does not exist.
Resolution
To work around this problem:do not use spaces in the name
-or-
make sure that the database name you are pasting in does not contain a leading space character.