Polling Servers
When multiserver administration is implemented, target servers periodically contact the master server to upload information on jobs that have been executed, and download new jobs. The process of contacting the master server is called server polling, which takes place at regular polling intervals.
Polling Intervals
The polling interval (one minute by default) controls how frequently the target server connects to the master server to download instructions and upload the results of job execution.
When a target server polls the master server, it reads the operations assigned to the target server from the sysdownloadlist table in the msdb database. These operations control multiserver jobs and various aspects of the behavior of a target server. Examples of operations include deleting a job, inserting a job, starting a job, and updating the polling interval of a target server.
Operations are posted to the sysdownloadlist table in either of the following ways:
- Explicitly by using the sp_post_msx_operation stored procedure.
- Implicitly by using other job stored procedures.
If you use job stored procedures to modify multiserver job schedules or job steps, or SQL Distributed Management Objects (SQL-DMO) to control multiserver jobs, issue the following command after modifying a multiserver job's steps or schedules:
EXECUTE msdb.dbo.sp_post_msx_operation 'INSERT', 'JOB', '<job id>'
Issue this command keeps the target servers synchronized with the current job definition.
You do not have to post operations explicitly if you use the following:
- Microsoft SQL Server Management Studio to control multiserver jobs.
- Job stored procedures that do not modify job schedules or job steps.