Why is the report analyzer showing that no indexes are used, despite the filter being displayed as indexed?
Oracle RightNow CX, All versions
The filter used column is populated dynamically depending on the filter values used. For example, if you add a filter on the contact ID in the incidents table (incidents.c_id) and set it to be blank (all contacts), the index on this field will not be used. If you select a particular value as shown in the screenshot below the query will be able to use the index.
Depending on the filter values and which filters are used, the "Index Used" column will give an indication if the index is usable in the current query.
Note: If a column is indexed it does not necessarily mean that the index can be efficiently used by the database query running behind the report. Adding specific filter values changes the syntax in the underlying query and may make it more likely for the index to be used. However, there is no way to guarantee that the specific index will be used.
For more information relating to indexing, refer to Impact of indexing a custom field.