} else {
				return errNonNumericArg(funcName)
			}
		}
	}

	// Mark that we have seen one non-null value.
	isFirstRow := false
	if !e.aggregate.seen {
		e.aggregate.seen = true
		isFirstRow = true
	}

	switch funcName {
	case aggFnCount:
		// For all non-null values, the count is incremented.
		e.aggregate.runningCount++

	case aggFnAvg, aggFnSum:
		e.aggregate.runningCount++