The 'Prefetch Size' and 'Max Cursor Size' is used for DB2 database. But there are some cases where Max Cursor Size alone has been used for Oracle database. The possible workaround is to run a default PDQ. You may like to default to a *No Records* Query using a search specification on an indexed field but with a value that we know does not exist. This will speed up performance for the first click. The user will then be required to query based on their criteria. You could refer to the PDQ "* * Null Query" for Account business object in standard Siebel application. Another possible way is to use scripting E.g. the PreQuery event could be used to check the query string and exclude those columns that have no index assigned by the script. According to this posting  It should work for oracle as well. But in case of EAI Adapter it just ignores such settings at business component level. The Max Cursor Size & Pre Fetch Size properties at Business component level are ignored by the Siebel EAI Adaptor.Only if they are set at Data Source it will work.