Implementations of this method should only aggregate existing reports of subperiods of the
current period. For example, it is more efficient to aggregate reports for each day of a
week than to aggregate each log entry of the week.
Use {@link Piwik\ArchiveProcessor::aggregateNumericMetrics()} and {@link Piwik\ArchiveProcessor::aggregateDataTableRecords()}
to aggregate archived reports. Get the {@link Piwik\ArchiveProcessor} instance using the {@link getProcessor()}
method.