Publication Information, Tracer Tokens (Transactional Publication, SQL Server 2005 and Later)
The Tracer Tokens tab allows you to validate connections and to measure the latency of a system that uses transactional replication. A token (a small amount of data) is written to the transaction log of the publication database, marked as though it were a typical replicated transaction, and sent through the system, allowing a calculation of:
- How much time elapses between a transaction being committed at the Publisher and the corresponding command being inserted in the distribution database at the Distributor.
- How much time elapses between a command being inserted in the distribution database and the corresponding transaction being committed at a Subscriber.
From these calculations, you can answer a number of questions, including:
- Which Subscribers take the longest to receive a change from the Publisher?
- Of the Subscribers expected to receive the tracer token, which, if any, have not received it?
Options
- Insert Tracer
Click to insert a tracer token in the transaction log at the Publisher.
Time inserted
Select a time at which a tracer token was inserted to display latency information from that time. By default, information from the most recent time is displayed.Note
Tracer token information is retained for the same time period as other historical data, which is governed by the history retention period of the distribution database. For information about changing distribution database properties, see How to: View and Modify Distributor Properties (SQL Server Management Studio).
- Subscription
The name of each subscription to the publication.
- Publisher to Distributor
The elapsed time between a transaction being committed at the Publisher and the corresponding command being inserted in the distribution database at the Distributor. A value of Pending indicates that the token has not yet reached the Distributor. If the pending state persists, ensure that the Log Reader Agent is running.
- Distributor to Subscriber
The elapsed time between a command being inserted in the distribution database and the corresponding transaction being committed at a Subscriber. A value of Pending indicates that the token has not yet reached the Subscriber. If the pending state persists, ensure that the Distribution Agent is running.
- Total Latency
The elapsed time between a transaction being committed at the Publisher and the corresponding transaction being committed at the Subscriber. This represents the end-to-end latency of the replication system for this Subscriber at this time. A value of Pending indicates that the token has not yet reached the Subscriber.
See Also
Other Resources
How to: Start and Stop a Replication Agent (SQL Server Management Studio)
How to: Start Replication Monitor (Replication Monitor)
Measuring Latency and Validating Connections for Transactional Replication
Monitoring Performance with Replication Monitor
Monitoring Replication with Replication Monitor
Replication Agents Overview