Which three statements are true about Global Sequences …

Which three statements are true about Global Sequences when connected to a physical standby database with
Real-Time Query enabled?

Which three statements are true about Global Sequences when connected to a physical standby database with
Real-Time Query enabled?

A.
If the CACHE option is set then the size of the cache must be at least 100.

B.
Their creation requires that a LOG_ARCHIVE_DEST_n parameter be defined in the standby that points
back to their primary.

C.
Their usage will always have a performance impact on the primary database.

D.
Their usage may have a performance impact on the physical standby database if the CACHE size is too
small

E.
They must have the NOORDER and CACHE options set.

Explanation:
B: the terminal standby should have a LOG_ARCHIVE_DEST_n parameter defined that points back to the
primary.
D: Because the standby’s requests for a range of sequences involve a round-trip to the primary, be sure to
specify a large enough value for the CACHE keyword when you create a sequence that will be used on anOracle Active Data Guard standby. Otherwise, performance could suffer.
E: In an Oracle Active Data Guard environment, sequences created by the primary database with the default
CACHE and NOORDER options can be accessed from standby databases as well.
https://docs.oracle.com/database/121/SBYDB/manage_ps.htm#SBYDB5164

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Chunn

Chunn

B, D, E

Explanation:

In an Oracle Active Data Guard environment, sequences created by the primary database with the default CACHE and NOORDER options can be accessed from standby databases as well. When a standby database accesses such a sequence for the first time, it requests that the primary database allocate a range of sequence numbers. The range is based on the cache size and other sequence properties specified when the sequence was created. Then the primary database allocates those sequence numbers to the requesting standby database by adjusting the corresponding sequence entry in the data dictionary. When the standby has used all the numbers in the range, it requests another range of numbers.

The primary database ensures that each range request from a standby database gets a range of sequence numbers that do not overlap with the ones previously allocated for both the primary and standby databases. This generates a unique stream of sequence numbers across the entire Oracle Data Guard configuration.

Because the standby’s requests for a range of sequences involve a round-trip to the primary, be sure to specify a large enough value for the CACHE keyword when you create a sequence to be used on an Oracle Active Data Guard standby. Otherwise, performance could suffer.

Also, be sure the terminal standby has a LOG_ARCHIVE_DEST_n parameter defined that points back to the primary.

Sequences created with the ORDER or NOCACHE options cannot be accessed on an Oracle Active Data Guard standby.

https://docs.oracle.com/database/121/SBYDB/manage_ps.htm#SBYDB5164

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