Monitoring replication latency

After you start a replication set, you can view the latency of replication, or the time that it takes for transactions to move from the source to the target database.

The status page for each replication set depicts latency with a multicolored graph in the center of the screen that gives you an at-a-glance view of the different types of replication latency, as shown in Figure 1.

At the top of the Average Replication Latency area, the most current average overall latency for the replication set is shown in large type. Overall latency (also known as end-to-end latency) measures the elapsed time between a transaction being committed at the source database and a replicated copy of that transaction being committed at the target database.

The individual line in the chart represents point-in-time latency, the time difference between the last consistency point and the current time. The three solid colors in the chart represent capture latency, apply latency, and transport latency:

Capture latency

The average elapsed milliseconds between the time transactions were committed to the source table and the time the transactions were sent to the target.

Apply latency

The average elapsed milliseconds that it takes the replication programs at the target to read received transactions and commit them to target tables.

Transport latency

The average elapsed milliseconds that it takes for transactions to be transported from the source server to the target server.

You can hover the cursor over the latency graph to view detailed time statistics for each type of latency, as shown in Figure 2.

You can change the time period for the statistics by clicking the clock icon in the upper right corner of the Replication Set Monitoring area.