View the Exhibit. 
Examine the following command that is executed for the TRANSPORT table in the SH schema:
SQL> SELECT DBMS_STATS.CREATE_EXTENDED_STATS(‘sh’, ‘customers_obe’, ‘(country_id,
cust_state_province)’) FROM dual;
Which statement describes the significance of this command?
A.
It collects statistics into the pending area in the data dictionary.
B.
It creates a virtual hidden column in the CUSTOMERS_OBE table.
C.
It collects statistics with AUTO_SAMPLE_SIZE for ESTIMATE_PERCENT.
D.
It creates a histogram to hold skewed information about the data in the columns.
Reason for ‘B’.
Repeat the command, see conflict with initial virtual column that was created, an extension has already been created. See below…
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 – 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> select dbms_stats.create_extended_stats(‘sh’,’customers_be’,'(country_id,cust_state_province)’) from dual;
DBMS_STATS.CREATE_EXTENDED_STATS(‘SH’,’CUSTOMERS_BE’,'(COUNTRY_ID,CUST_STATE_PRO
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SYS_STUJGVLRVH5USVDU$XNV4_IR#4
SQL> select dbms_stats.create_extended_stats(‘sh’,’customers_be’,'(country_id,cust_state_province)’) from dual;
select dbms_stats.create_extended_stats(‘sh’,’customers_be’,'(country_id,cust_state_province)’) from dual
*
ERROR at line 1:
ORA-20007: extension (country_id,cust_state_province) already exists in the table
ORA-06512: at “SYS.DBMS_STATS”, line 6674
ORA-06512: at “SYS.DBMS_STATS”, line 28195