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oca about a question [message #556838] Wed, 06 June 2012 21:24 Go to next message
andy huang
Messages: 498
Registered: July 2011
Senior Member
Dear all,
In the OCA of 10g,there is a question just as flowing, the answer the C and F, can you explain the answer F?

15. User Scott has updated the salary of one of the employees in the EMPLOYEES table and has not committed
the transaction. What are the two types of locks that this scenario would lead to? (Choose two.)
A) null lock on the row being updated
B) null lock on the table containing the row
C) ROW SHARE lock for the row being updated
D) ROW EXCLUSIVE lock for the row being updated
E) shared row-exclusive lock for the row being updated
F) a shareable table lock for the table containing the row
G) exclusive table-level lock for the table containing the row
Re: oca about a question [message #556848 is a reply to message #556838] Thu, 07 June 2012 00:39 Go to previous messageGo to next message
matthewmorris68
Messages: 258
Registered: May 2012
Location: Orlando, FL
Senior Member

Every DML operation creates a lock against the rows being updated and a lock against the table being updated. The row locks prevent other users from updating the same rows simultaneously through another DML operation. The table lock prevents the table from being altered via a DDL operation (like someone dropping the table, or altering one of the columns) while the DML transaction is active.
Re: oca about a question [message #556851 is a reply to message #556848] Thu, 07 June 2012 01:25 Go to previous messageGo to next message
andy huang
Messages: 498
Registered: July 2011
Senior Member
Thanks!
Re: oca about a question [message #556855 is a reply to message #556851] Thu, 07 June 2012 01:38 Go to previous message
Michel Cadot
Messages: 67294
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
And of course, locking mechanism is explained in details in Database Concepts.

You will not have any certification if you don't read the documentation.

Regards
Michel
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