Which two statements are true about transactions in Oracle Database 12c?

Question

Options

• AMultiple transactions can use the same undo segment.
• BA transaction is assigned an undo segment when it is started.
• CMultiple transactions cannot share the same extent in an undo tablespace.
• DIf all the segments in an undo tablespace are used, transactions use system undo segments to

• A
  76% (37)
• C
  8% (4)
• D
  16% (8)

Explanation

https://docs.oracle.com/database/121/CNCPT/logical.htm#CNCPT305 Undo Segments and Transactions When a transaction starts, the database binds (assigns) the transaction to an undo segment, and therefore to a transaction table, in the current undo tablespace. In rare circumstances, if the database instance does not have a designated undo tablespace, then the transaction binds to the system undo segment. Multiple active transactions can write concurrently to the same undo segment or to different segments. For example, transactions T1 and T2 can both write to undo segment U1, or T1 can write to U1 while T2 writes to undo segment U2. Conceptually, the extents in an undo segment form a ring. Transactions write to one undo extent, and then to the next extent in the ring, and so on in cyclical fashion

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