Using a4j to load a rich:dataTable after the page loads

Question

I have a rich:dataTable that calls a session bean which executes an SQL query to generate the data to be displayed in the table. Something simple like:
<rich:dataTable rowClasses="evenRow,oddRow"
rows="30"
value="#{Bean.items}"
var="items">
where Bean.getItems() performs an SQL query and returns List<Item>.
The problem is that the query takes a long time to execute (~45 seconds) and I'd like the page to initially load while the query is being executed, displaying a spinner while it loads. Once the query is done, I'd like to update the initially empty table using ajax.
I set up a spinner using a4j:status and it works fine after the page initially loads (using a rich:datascroller).
However, the page will not initially load until the query completes, which is a problem because the query is so slow. What happens is the user clicks on the "List Items" tab from my site's homepage, sits there on the same page for 45 seconds with absolutely no visual indication that anything is happening, and then finally is taken to the list of items page.
What is needed to make the dataTable load via AJAX the first time, as well as all subsequent times?
Thanks!
Edited by: rcrowell on Sep 8, 2008 5:42 PM

Answer 1

rcrowell wrote:
The issue isn't the PK of the table; the query is joining across many tables and aggregating data from one table in particular with millions of rows. The table has paging, but again that won't help the timinig issues due to the aggregation that must be performed on a large table.
Surely there must be a way to get the dataTable to always load its data via ajax, and not only after the first time.Well JSF does not have AJAX built-in, so why would there be? Perhaps one of the AJAX-based frameworks has this. I imagine it wouldn't be hard to do with the existing AJAX frameworks even without a built-in component specifically for it. Trigger an AJAX action on load which rerenders a panel which will only contain the dataTable upon the rerendering.
>
I think I could do it by adding a 'dataTableRendered' variable to the bean and using a jsFunction to set this variable to True when the page loads, but I'm looking for a better way. (I'm also not 100% sure this would do what I want.)