Hi

We can configure the given database to update data asynchronously in SQL server 2005. This was not possible in SQL server 2000. In SQL Server 2000 we had to update the statistics synchronously. This is till the default in SQL server 20005.

If a given query request for the update of statistics without this option set, then the query will have to wait for till the statistics are updated and then be executed.

But if set the option for AUTO_UPDATE_STATISTICS_ASYNC then the query will not wait for the update of the statistics but will execute with the current statistics and at the same time a background process will start the automatic updation of the statistics as soon as possible. This will not prevent any query request.

Once this background operation is complete new query request will use the new updated statistics. One very important thing to note here is that this option comes into play only for Auto Update Statistics event and not when manually updating statistics or on demand updating of statistics on request by a user.

Thanks

Vikram