You create a table with the PERIOD FOR clause to enable the use of the Temporal Validity feature of Oracle Database 12c. Examine the table definition: Which three statements are true concerning the…

Question

Exhibit

Options

• AThe valid time columns employee_time_start and employee_time_end are automatically created.
• BThe same statement may filter on both transaction time and valid temporal time by using the AS OF
• CThe validtimecolumns are not populated by the Oracle Server automatically.
• DThe validtimecolumns arevisible by default when the table is described.
• ESetting the session valid time using

• A
  84% (16)
• C
  5% (1)
• D
  11% (2)

Explanation

Oracle 12c Temporal Validity (PERIOD FOR clause) has the following true behaviors: (A) If the start and end column names specified in PERIOD FOR do not already exist in the table, Oracle automatically creates them as hidden columns-they are not required to be pre-declared. (B) A single query can simultaneously filter on both transaction time (using AS OF TIMESTAMP or AS OF SCN against the undo/flashback layer) and valid time (using AS OF PERIOD FOR <period_name>), combining both temporal dimensions. (E) Using ALTER SESSION SET (or DBMS_FLASHBACK_ARCHIVE procedures) to set a session-level valid time causes Oracle to automatically filter rows based on whether the valid time period overlaps the specified time, transparently applying to all queries in that session. Option C is false-Oracle does NOT automatically populate the valid time start/end columns; the application is responsible for inserting and updating those values. Option D is false-when Oracle implicitly creates the period columns, they are hidden columns and do not appear in a standard DESCRIBE output.

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