Primefaces dataTable Sorting does not seem to work - jsf

Question

I am having difficulties sorting a dynamic dataTable
dataTable
<h:form prependId="false" id="Main_Form">
<p:dataTable id="dataTable" var="c" value="#{databaseSearch.customerList}"
paginator="true" rows="10" paginatorAlwaysVisible="false"
paginatorTemplate="Page {CurrentPageReport} {FirstPageLink} {PreviousPageLink} {PageLinks} {NextPageLink} {LastPageLink} Rows per page {RowsPerPageDropdown}"
rowsPerPageTemplate="5,10,15,30" draggableColumns="True">
<p:column sortBy="#{c.machine}" headerText="Machine">
<h:outputText value="#{c.machine}" />
</p:column>
<p:column sortBy="#{c.company}" headerText="Company">
<h:outputText value="#{c.company}" />
</p:column>
<p:column sortBy="#{c.contact}" headerText="Contact">
<h:outputText value="#{c.contact}" />
</p:column>
<p:column sortBy="#{c.phone}" headerText="Phone">
<h:outputText value="#{c.phone}" />
</p:column>
<p:column sortBy="#{c.email}" headerText="Email">
<h:outputText value="#{c.email}" />
</p:column>
<p:column exportable="false" headerText="Modify">
<center>
<p:commandButton id="basic" value="Update"
action="#{updateEntry.setMachine(c.machine)}"
oncomplete="dlg1.show();"
styleClass="ui-Machinebutton" update=":Update_Entry"/>
<p:tooltip for="basic" value="Update/Delete Database Entry"
showEffect="fade" hideEffect="fade" />
</center>
</p:column>
</p:dataTable>
</h:form>
I am using a #SessionScoped bean where databaseSearch.customerList would query the database and populate the dataTable. When I click on the column name to sort, the sort arrow mark changes but the table contents do not sort.
I am using PF 3.4.2

Answer 1

If you are querying your database in your getCustomerList method in every request this will not work. You may try with a local variable
public class DatabaseSearch{
private List<C> customerList;
public List<C> getCustomerList () {
if (customerList == null)
customerList = dao.getcustomerList();
return customerList ;
}
}