Examine the parameter for your database instance:

You generated the execution plan for the following query in the plan table and noticed that the nested loop join was done. After actual execution of the query, you notice that the hash join was done in the execution plan:

Identify the reason why the optimizer chose different execution plans.

• A.The optimizer used a dynamic plan for the query.
• B.The optimizer chose different plans because automatic dynamic sampling was enabled.
• C.The optimizer used re-optimization cardinality feedback for the query.
• D.The optimizer chose different plan because extended statistics were created for the columns used.

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Examine the parameters for your database instance:
NAMETYPE VALUE
-------------------------- ------------------------------- ---------------------------
undo_management string AUTO
undo_retentioninteger 12 00
undo_tablespace string UNDOTBS1
You execute the following command:
SQL> ALTER TABLESPACE undotbs1 RETENTION NOGUARANTEE;
Which statement is true in this scenario?

• A.An attempt is made to keep inactive undo for 1200 seconds but transactions may overwrite the undo before that
  ti me has elapsed.
• B.Inactive undo data is retained for 1200 seconds even if subsequent transactions fail due to lack of space in the undo
  tablespace.
• C.Undo data is written to flashback logs after 1200 seconds.
• D.You can perform a Flashback Database operation only within the duration of 1200 seconds.

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On your Oracle Database, you issue the following commands to create indexes:
SQL > CREATE INDEX oe.ord_customer_ix1 ON oe.orders (customer_id, sales_rep_id)
INVISIBLE;
SQL> CREATE BITMAP INDEX oe.ord_customer_ix2 ON oe.orders (customer_id, sales_rep_id);
Which two statements are true?

• A.Only the ORD_CUSTOMER_IX1 index created.
• B.Both the indexes are updated when a row is inserted, updated, or deleted in the
  ORDERS table.
• C.Both the indexes are created: however, only ORD_CUSTOMERS_IX1 is used by the optimizer for queries on the ORDERS table.
• D.The ORD_CUSTOMER_IX1 index is not used by the optimizer even when the
  OPTIMIZER_USE_INVISIBLE_INDEXES parameters is set to true.
• E.Both the indexes are created and used by the optimizer for queries on the ORDERS table.
• F.Both the indexes are created: however, only ORD_CUSTOMERS_IX2 is used by the optimizer for queries on the ORDERS table.

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You must track all transactions that modify certain tables in the sales schema for at least three years.
Automatic undo management is enabled for the database with a retention of one day.
Which two must you do to track the transactions?

• A.Enable supplemental logging for the database.
• B.Specify undo retention guarantee for the database.
• C.Create a Flashback Data Archive in the tablespace where the tables are stored.
• D.Create a Flashback Data Archive in any suitable tablespace.
• E.Enable Flashback Data Archiving for the tables that require tracking.

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Which statement is true about a database in ARCHIVELOG mode?

• A.A Fast Recovery Area (FRA) must be configured for the database.
• B.Full database backups can be performed when the database is opened.
• C.Online redo log files have to be multiplexed before putting the database in ARCHIVELOG mode.
• D.All backups taken prior to switching to ARCHIVELOG mode can be used to perform complete recovery.

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