Comparison of Query Methods

• Specify an array of PerfQuerySpec objects.
• An unset PerfQuerySpec.metricId property produces results for all counters defined for PerfQuerySpec.entity.
• PerfQuerySpec.maxSample is ignored for historical statistics.

You can use this method to retrieve historical statistics; you can also use it as a raw data feed. For information about retrieving the raw data collected on ESXi servers, see Using the QueryPerf Method as a Raw Data Feed.

• Method works only at the host level. You can use a single call to the QueryPerfComposite method to retrieve performance data for a host and its virtual machines.
• Specify a single PerfQuerySpec object.
• You must specify a list of performance metrics to identify the data to be retrieved (PerfQuerySpec.metricId).
• You cannot specify PerfQuerySpec.maxSample.

This method is designed for efficient client-server communications. QueryPerfComposite usually generates less network traffic than QueryPerf because it returns a large-grained object, a PerfCompositeMetric data object, that contains all the data.