Answer:

Check the definition of the plan_table, you will find a couple of columns with
names like partition_start and partition_stop. print this as part of your execution plan, and they will give you an idea of how (or what) partition elimination is taking place.

Ideally you will see literal numbers as the partition start and stop values, these correspond to the first and last partition_position (user_tab_partitions) actually accessed by the query.

You may see 'KEY' 'KEY' which tends to indicate that static elimination could
not be used, but run-time probing was used on indexes to eliminate partition searches a cheaply as possible.

Also the OPTION column should give you RANGE or SINGLE to show whether
oracle expects a single or many partitions in step N+1 to be accessed to feed step N
 

Question:

>Is there a way to tell it partition pruning has occurred and which
>partitions were accessed during a query.  I can see in the explain plan
>the PARTITION (CONCATENATED) but it doesn't tell me to what extent the
>pruning occurred.  SQL TRACE does seem to help here either.
>
>I am testing a a partitioning scheme that uses a multi-column partition
>key on 2 dates in a table.  I am not sure if this will even work and
>want to check if what I want is occurring.
>
>Thanks
>