單項選擇題

The user SCOTT executes the following command successfully to increase the salary values in one of his sessions：
SQL> UPDATE emp SET sal=sal*1.15 WHERE deptno=20;
Before SCOTT ends the transaction， user HR who has the privileges on EMP table executes a query to fetch the salary details but finds the old salary values instead of the increased values.
Why does HR still see the old data？（）

A.because of redo data from redo log file
B.because of data from database buffer cache
C.because of data from a temporary tablespace
D.because of undo data from the undo tablespace

你可能感興趣的試題

單項選擇題

Your database is running under automatic undo management and the UNDO_RETENTION parameter is set to 900 sec. You executed the following command to enable retention guarantee：
SQL> ALTER TABLESPACE undotbs1 RETENTION GUARANTEE;
What effect would this statement have on the database？（）

A.The extents in undo tablespace retain data until the next full database backup.
B.The extents containing committed data in the undo tablespace are never overwritten.
C.The extents which no longer contain uncommitted data in the undo tablespace are not overwritten for at least15 minutes.
D.The extents containing committed data in the undo tablespace are not overwritten until the instance is shut down.

多項選擇題

A user receives the following error while executing a query：
ORA01555：snapshot too old
Which two options can be the solutions to avoid such errors in future？（）

A.increase the size of redo log files
B.increase the size of the undo tablespace
C.increase the size of the Database Buffer Cache
D.increase the size of the default temporary tablespace
E.enable the retention guarantee for the undo tablespace

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你可能感興趣的試題

Your database is running under automatic undo management and the UNDO_RETENTION parameter is set to 900 sec. You executed the following command to enable retention guarantee： SQL> ALTER TABLESPACE undotbs1 RETENTION GUARANTEE; What effect would this statement have on the database？（）

A user receives the following error while executing a query： ORA­01555：snapshot too old Which two options can be the solutions to avoid such errors in future？（）

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Your database is running under automatic undo management and the UNDO_RETENTION parameter is set to 900 sec. You executed the following command to enable retention guarantee：
SQL> ALTER TABLESPACE undotbs1 RETENTION GUARANTEE;
What effect would this statement have on the database？（）

A user receives the following error while executing a query：
ORA01555：snapshot too old
Which two options can be the solutions to avoid such errors in future？（）