How to update specific row in Primefaces datatable

Primefaces 3.5, Mojarra 2.1.14. This is my PF datatable, it contains one non-editable boolean column named 'automatic', and editable 'label' column:

<p:dataTable value="#{bean.contents}" paginator="true" var="row" 
  editable="true" editMode="cell" rows="25" rowsPerPageTemplate="10,25,50" id="list">
    <p:column>
        <f:facet name="header"><h:outputText value="header1" /></f:facet>
        <p:selectBooleanCheckbox value="#{row.automatic}" disabled="true" id="isAutomatic"></p:selectBooleanCheckbox>
    </p:column>
    <p:column>
        <f:facet name="header"><h:outputText value="header2" /></f:facet>
        <p:cellEditor>
            <f:facet name="output">
                <h:outputText value="#{row.label}"></h:outputText>
            </f:facet>
            <f:facet name="input">
                <p:inputText value="#{row.label}"></p:inputText>
            </f:facet>
        </p:cellEditor>
    </p:column>
    <p:ajax event="cellEdit" process="@this" listener="#{myBean.onEditLabel}" update="isAutomatic"/>
</p:dataTable>

Cell edit event listener:

public void onEditLabel(CellEditEvent event) {
    Object oldValue = event.getOldValue();
    Object newValue = event.getNewValue();

    if(newValue != null && !newValue.equals(oldValue)) {
        DataTable s = (DataTable) event.getSource();
        MyEntity d = (MyEntity) s.getRowData();
        try {
            d.setAutomatic(false);
            myDAO.save(d);
            addMessage("Change saved!");
        } catch (Exception ex) {
            addErrorMessage("Label could not be saved!");
            getFacesContext().validationFailed();
        }
    }
}   

The cell editor works, sends data to listener, and it is