Index vs. Sequential Reads Metric

The index vs. sequential reads plot presents the proportion of reads that use an index over the total number of reads across all databases (schemas) on the main server.  

In general, you can optimize queries across large tables by using an index. View the MySQL query statistics on the Logs & Queries tab and the EXPLAIN statement to identify slow queries that may benefit from the addition of an index.

For more information on monitoring MySQL clusters, see How to Monitor MySQL Database Performance.