Which three statements are true about sequences in a single instance Oracle database? (Choose three.)
Which three statements are true about sequences in a single instance Oracle database? (Choose three.)
Sequences in an Oracle database can always have gaps, which occur due to reasons such as caching and concurrent usage. If a sequence's cached values are unallocated and the instance shuts down, those values are lost. Additionally, a sequence can issue duplicate values if it is defined to cycle back to its start point after reaching the maximum value.
Agree with A, C and D.
ACD are correct
Answer is ACD
https://www.examtopics.com/discussions/oracle/view/20160-exam-1z0-071-topic-2-question-27-discussion/
F-FALSE: When a sequence number is generated, the sequence is incremented, independent of the transaction committing or rolling back. A-TRUE: If two users concurrently increment the same sequence, then the sequence numbers each user acquires may have gaps, because sequence numbers are being generated by the other user
I agree ACD C-TRUE:when an instance abnormally shuts down (for example, when an instance failure occurs or a SHUTDOWN ABORT statement is issued), sequence numbers that have been cached but not used are lost. The CACHE clause preallocates a set of sequence numbers and keeps them in memory so that sequence numbers can be accessed faster D-TRUE: If the sequence is cycle it can generate duplicate values.
https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/CREATE-SEQUENCE.html
B is wrong -> "Sequence numbers are generated independently of tables, so the same sequence can be used for one or for multiple tables" https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/CREATE-SEQUENCE.html