Explain plan in Oracle

I want to show the usage of an explain plan in Oracle. This will be shown in Oracle 12c. I will create a table and a sql statement. This sql statement will be analysed in a so-called explained plan that shows how Oracle will process the query. To do so, I first created a big table “Groot” in Oracle. Upon that I created an index “GrootIndex” with create index grootIndex on groot(n).
The explain plan is created with (select * from C##HR.GROOT where n=600000; being the sql statement) :

explain plan for
select * from C##HR.GROOT
where n=600000;

The results are then shown with:

select object_name, operation, options, object_type, optimizer, id 
from (
select   object_name, operation, options, object_type, optimizer, id, dense_RANK() OVER (PARTITION BY OPERATION order by   PLAN_ID DESC) rn
from plan_table)A 
where rn=1
order by id;

The results are:

OBJECT_NAME	OPERATION	    OPTIONS
	        SELECT STATEMENT	
GROOT	        TABLE ACCESS	    BY INDEX ROWID BATCHED
GROOTINDEX	INDEX	            RANGE SCAN

One might see that the sql uses the index. Based on the rowid =found herein, the sql accesses table Groot with the rid to retrieve the rows that were requested.

Or – alternatively, you may use:

select * from table(dbms_Xplan.display());

that provides something like:

A final remark: these results can also be seen in SQL developer. In the tool bar, one may notice small buttons that allow such direct analysis.