Hi,
There isn't a direct equivalent API report for the data available in the "Hour of day" view in the Dimensions tab. You could consider using
Account Performance Report,
AdGroup Performance Report, or
Campaign Performance Report reports and include the HourOfDay field in the report definition to segment the report based on the hour of day.
Questions related to Pentaho are not in scope for this forum. You could consider contacting
Pentaho support for any further questions.
Regards,
Shwetha, AdWords API Team.