Hi,
Index Range accesses are ranges on indexes to find the rows to access the table afterwards.
Isolated Index Range accesses are used for Index Only strategies which means all data which is in the select list qualified can be fetched by the index only access - this means no additional access on the base table is necessary.
E..g select key_column1,key_column2, Index_col1,Index_col2
where index_col2 > <value>
Because of the fact that primary key columns are stored as seperator in the index b* tree as well, you have all needed information on the index. No additional access on base table.
Regards, Christiane