On your Oracle 12c database, you Issue the following commands to create indexes
SQL > CREATE INDEX oe.ord_customer_ix1 ON oe.orders (customers_id, sales_rep_id)
INVISIBLE;
SQL> CREATE BITMAP INDEX oe.ord_customer_ix2 ON oe.orders (customers_id, sales_rep_id);
Which two statement are correct?
A.
Both the indexes are created; however, only the ORD_COSTOMER index is visible.
B.
The optimizer evaluates index access from both the Indexes before deciding on which index to
use for query execution plan.
C.
Only the ORD_CUSTOMER_IX1 index is created.
D.
Only the ORD_CUSTOMER_IX2 index is created.
E.
Both the indexes are updated when a new row is inserted, updated, or deleted In the orders
table.
Explanation:
11G has a new feature called Invisible Indexes. An invisible index is invisible to the
optimizer as default. Using this feature we can test a new index without effecting the execution
plans of the existing sql statements or we can test the effect of dropping an index without dropping
it.
Though the option-A and E is correct, the wording of A is not correct.
The correct statement would be:
Both the indexes are created; however, only the ord_customer_ix2 index is visible.
Same question but different responses as #118.
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